NO one has any forced share in her share.
She can dispose by her sweet will.
Your father and uncle are her sons.
If she does not dispsoe in her life time then by inheritance it shall devolve upon her sons, daughters (since her husband has pre-deceased)..............
Ultimately it is going to come to your father and then may come to you.
Serve her with affection and care and she may leave it for her sons/daughters and may not diispose in her life time in anyone else's favor.
