Firstly the concept of ancestral property is not applicable to Christians
If your father is shown as owner in the land revenue and property records then you being his legal heir, have an undivided share in his property
To enforce your share you need to file a partition suit
Though the members of the family seem to have superficially divided and partitioned the house and are living in their respective units, but that does not mean you have lost your right. You and all other members have undivided right in all the units of the house, so also the land on which the building stands
By members, i mean only legal heirs of original owner
I am not able to understand why lawyers here advised to not go for partition because redevelopment was on the anvil?
If the property is duly partitioned and the share of each member is determined, then that will infact aid in redevelopment, because the builder will know exactly what he has to give to each member, in terms of new flat and redevelopment benefits
Its true that a partition suit takes time to resolve, but then not going for it, is not the solution either, especially when your rights in the house are being denied by other members
Also forcefully getting into the house will only invite legal trouble for you
So either sit with your family members and cull out a partition plan and if they dont relent then you can issue a legal notice to them to see what they have to respond and if there is no outcome, then file a partition suit
There are cases which i have seen that the members who reside in undivided House sell it or give for redevelopment without consulting all members and the member who was left out, then wakes up from his slumber and files a partition suit to claim his share, by which time the property already changes hands