He gave one of his wives a house with the agreement of his children from his other wife; after he died, they objected. Is the gift valid or is it part of the estate?

No File Exists
Check below answers in case you are looking for other related questions:
The obligation to treat co-wives fairly in giving gifts
Accepting a gift from a kaafir

No File Exists
Related Answers:
He gave her an engagement ring and they differed as to whether it was a gift or a loan
Her father paid her university fees, then the university returned the fees as a prize to her; does her father have the right to take them?
His work gave him the task of buying an apartment; does he have any right to the broker’s fee?
The obligation to treat co-wives fairly in giving gifts
Accepting a gift from a kaafir

Recommended answers for you:
Yoga, its origins and the ruling on practising it
Ruling on sexual fantasies
Du’aa’ for completing the Qur’aan (khatam)
Using toothpaste whilst fasting
Rings and chains for men