Ref. No. 953/41-000
In the name of Allah the most Gracious the most Merciful
The answer to your question is as follows:
As long as the father is alive, the children have no share in his property. Children’s demand to give them their shares in his lifetime is totally illegal in shariah. Father has full authority over his property to give it to any relatives and friends and also to masjid and madrasa. Nevertheless, one should inculcate in his mind that mirath is a sharia right, hence no one can overlook it. Therefore, if a father gives away his property to his relatives merely with the intention to deprive some or all of his children of mirath completely, then it is unlawful and a great sin.
الارث جبری لا یسقط بالاسقاط ( العقود الدریۃ 2/51)
And Allah knows best
Darul Ifta
Darul Uloom Waqf Deoband