Father in law is at liberty to bequeath his property by will to whomsoever he pleases 

2) he can also execute gift deed during his lifetime in favour of one daughter 

3) if he dies intestate ie without will his wife and children would inherit property equally 

1. It's not clear in your narration as to whether your father-in-law is alive or dead and if dead, was it intestate death or not.

2. Assuming that your father-in-law's death was an intestate (without executing a WILL) one, then the property would devolve equally to his Class-1 legal heirs, his wife and children. In the instant case 1/4th share to each.

3.  If it's on the basis of intestate death, then one of the legal heirs cannot take the entire property, unless and until other legal heirs execute a registered Release Deed relinquishing their share over the property in favour of their family member.

Is the Father in law alive? Is it ancestral property or self acquired property. You can file a suit through your husband and claim a share in the property. 

If father in law is alive, none have any right and FIL can give his property to any. On his intestate demise, you husband will inherit 1/3rd share in property.

1. An Hindu has complete & inherent right to claim share of his Late Father's property in EQUAL proportions, PROVIDED Father had not executed any WILL.

2. In case instant both daughters and one, shall have EQUAL rights to claim their late Father's property and one single legal heir CANNOT claim the entire property.

3. Till Husband (son of Father) is alive, you was Wife & your Son CANNOT stake claim /right over Father-in-Law's property.  Means only Husband can stake claim on his Father's property.  IF husband is not alive, THEN husband's share can be claimed by his Wife & Son in equal portions. 

The property on your father's name shall be his own and absolute property. It cannot be claimed by anyone as a right for any reason at least not during his lifetime.

Therefore,m if your father is alive then your sister nor you nor anyone claim any share in it s a right.

If he is not living and is reported to have died intestate then all his legal heirs consisting his wife, children and mother shall be entitled to an equal share in the properties left behind by him.

If your father in law died intestate legal heirs Daughter's  Son can claim equal share in said property. Your husband can file partition suit before jurisdictional court.

See in life of father he is absolute owner after his demise without will all legal heirs that is son daughter and wife has equal rights. In case he makes will or transfer in his life then in accordance to that property shall be distributed.

1. Yes you can definitely claim 1/3 share from self acquired properties of your father in law after his death if he dies intestate(without any will) 

2. You cannot claim any share from his properties during his life or if he writes a will in which you and your husband are not beneficiaries. 

3. Your husband can claim share from Ancestral property of your father in law.

Dear Sir,

During the lifetime of a person if that property is his self acquired property it cannot be snatched away forcefully by anybody but he can execute any document in favour of anybody of his choice.

Yes you have right. She can't claim alone