if father was suffering from dementia and you have evidence to back your claim father was not mentally for to execute the will 

2) litigation is long drawn process and suit may take 10 years to be disposed of 

3) on mother demise you have 40 per cent share in property 

4) you are at liberty to sell your share in property however your siblings may seek orders  to set aside sale on grounds that in case of sake you have only 40 per cent share 

5) C can execute will bequeathing his share in property during his lifetime 

You can do the point no 1 accepting and later after demise of mother go forward but once after acceptance you can’t later challenge the same will

C may not be married but on demise of your mother he will have share in property as per will.

on his demise intestate property would devolve on his siblings 

It is necessary to peruse will to advise further 

The Will states that your mother is vested with life interest.

This implies your mother has a life interest (the right to live there or enjoy the property) until her passing. No division or sale can happen without violating the will until then.

Even though your father specified square footage and floors, a house is structurally a single entity. Unless the property is officially partitioned into separate legal titles with the local municipal authority (which requires independent utility connections, structural safety approvals, and separate tax assessments), you cannot easily sell "1,100 sq. ft. of a ground floor" to an outside buyer. Most buyers and banks will not touch a fractured property without a clear, independent title deed and it can be considered to be defective title.

The joint conclusion clause acts as a safety valve written into the will. It says if you jointly agree that physical distribution is impossible, you sell the whole house. If you try to sell your part independently, siblings B and C could legally block the sale by arguing that the property cannot be physically or legally split, thereby forcing the "sell the whole house and split 40/30/30" clause into effect.

If you accept the will, you are bound by its terms, including the risk of being forced into that 40/30/30 split if a joint physical division fails.

If you choose Option 1 (Contest the Will) and the legal battle outlives sibling C, what happens to C's share depends entirely on when C passes away relative to the final court judgment.

Since C is unmarried and your father has passed, C's primary legal heir under most succession laws (like Hindu Succession Act or standard civil laws) would be your mother.

If your mother is also no longer alive at that point, C’s share would be divided equally among the surviving siblings (you and B). It does not automatically "go back to the estate" to benefit you exclusively; it is treated as C's personal asset passing to C's heirs.

If the court rules that the will is invalid (due to your father's dementia), the property is treated as if your father died intestate (without a will). Then the intestate succession law will prevail.

You mentioned siblings B and C are open to taking proceeds in cash, which you oppose. In real estate transactions, demanding "cash" (unaccounted or under-the-table money) is often an attempt to evade capital gains tax or stamp duty.

Engaging in undocumented cash transactions carries severe financial and legal penalties. If the property is sold as a whole, insist that all transactions go through official banking channels (check, bank transfer) to protect yourself from legal liability.

In legal terms, a will does not need to specify what happens to a beneficiary's heirs. If the will is accepted and C survives your father, C’s share becomes C’s personal property. What happens to that property if C passes away is governed by Succession Law, not your father’s will.

If a lawsuit to contest the will takes 10 years (which is, unfortunately, a very realistic timeline for property litigation in India), the question of who physically and legally holds the property during that decade depends entirely on who is currently in possession and whether an Executor was named.

The law generally prioritizes maintaining the status quo while a court decides the validity of the will. 

As long as your mother is alive, she holds the primary legal right to possess, reside in, and enjoy the property.

Even if you file a lawsuit to contest the will, the court will not throw your mother out. She holds the right to occupy the house or collect its rents to maintain herself during her lifetime.

If an Executor is named: Legally, the property "vests" in the Executor during the litigation period. They hold the legal title as a trustee until the court determines if the will is valid or invalid. The executor could be your mother, you, or even sibling C.

Dear Client,

The clause you quoted is a contingent provision that applies only if, after your mother's lifetime, all three children jointly conclude that the property cannot be divided as per the specific bequests in the will. In that situation, the will gives them an option to sell the whole house and divide proceeds as A = 40%, B = 30%, C = 30%. This does not give you (or any one heir) an independent right to force a sale or to sell your allotted portion unilaterally. However, the will does make a specific bequest of portions: A gets 1100 sq ft on the ground floor, B gets 600 sq ft on the first floor, and C gets 400 sq ft (both with independent access). Once your mother's life interest (if any) ends and the bequest vests, each heir becomes the owner of their specific portion, and you can sell your portion independently after mutation/partition, subject only to common-area rights and co‑ownership norms. The will does not override that; it only creates the sale option if all three jointly agree that division is not possible.

Since your father has already died with C alive, C's legacy does not lapse. C's 400 sq ft share vests in C at your father's death. If C later dies unmarried and without a will, C's property will devolve by intestate succession under the Hindu Succession Act: first to C's parents (here, your mother) and, if needed, then to Class II heirs (including your siblings). It does not automatically go back to your father's estate. The only situation where a share would lapse back to your father's estate is if C had died before your father (before the will took effect) and C had no lineal descendant. In that case, Section 105 of the Indian Succession Act provides for lapse, and the share would fall into the residue/back to the estate and then devolve by intestate succession among your mother and surviving children.

I hope this helps and if you have any further issues do not hesitate to contact us.

A final opinion would require examining the exact wording of the will, the nature of your mother's interest (life estate or otherwise), and whether your father was governed by the Hindu Succession Act, the Indian Succession Act, or another personal law. Under Indian law, when a person makes more than one will, the last valid will usually takes precedence and cancels any earlier wills that conflict with it.

Before you decide whether to accept the will, challenge it, or try to negotiate a settlement, gather the following documents and information: the death certificate; copies of all wills your father executed; his medical records related to dementia; and the dates when each will was executed.

A diagnosis of dementia 14 years ago does not automatically invalidate a will. The key question is whether your father had a sound disposing mind when he signed the will. If there are suspicious circumstances, the person presenting the will typically bears the burden of proving the testator was mentally capable at the time of execution.

our father's primary intention appears to be that A receives 1,100 sq. ft., B receives 600 sq. ft., and C receives 400 sq. ft. The sale-and-division provision is described only as a fallback arrangement. The phrase "jointly come to a conclusion" is significant. It suggests that all beneficiaries must reach a common decision, and that a sale is not automatic. Mere disagreement among beneficiaries may therefore prevent the sale clause from being invoked. Accordingly, there is a reasonable argument that the physical division is the primary bequest, and the sale clause applies only if all heirs agree that physical division or enjoyment is impracticable.

You can possibly accept the will and later sell your share, depending on how the property vests after your mother’s death.

If the will gives your mother a life interest and absolute ownership thereafter to A, B, and C, then the beneficiaries’ portions ordinarily vest after your mother’s death. In that situation you may generally transfer, sell, or gift your own share, subject to local building rules, identification of the specific portion, and whether the property has been legally partitioned and separately demarcated.

You cannot be compelled to follow a 40–30–30 split simply because B and C want cash. A strong argument is that the 40–30–30 formula applies only when all children jointly decide that partition is impossible. If you do not agree, that condition may never arise. Moreover, if the ground floor and first floor have independent access, as you mentioned, that fact strengthens the argument that physical enjoyment and separate occupation are feasible.

If you decide to contest the will, the following facts may be legally relevant:

1. Prior diagnosis of dementia.
2. Active participation of beneficiary C in preparation/execution.
3. Unequal distribution.
4. Existence of multiple wills.
5. Possible dependence of father on particular beneficiaries.

These are not by themselves sufficient to invalidate a will, but courts treat them as potentially suspicious circumstances requiring explanation.

You cannot accept part of will and reject the rest .

last will supersedes earlier wills 

obtain copy of his last will and get it vetted by a lawyer 

Firstly obtain a copy of the Will, get it scrutinized by an experienced lawyer in the local and then proceed as suggested because without knowing the contents of the Will any opinion rendered will be a misguidance.

Yes you can do the above 

as your mother is alive, the Will cannot be executed as she is the first beneficiary of that Will because as per the contents of the Will as enumerated by you " 

“ I hereby declare that after the lifetime of my wife, my children jointly come to a conclusion that it would not be possible to distribute the property in the manner I have devised, then I give them an opportunity to sell the whole house at the prevailing market rate and divide the proceeds with A getting 40%, B 30% and C 30%”
hence, there is no question of sharing the property by sale and distribute the proceeds of sell.