(1) Hiba is gifting someone a thing and giving it in his possession. With verbal Hiba, it is necessary to take out the gifted thing from ones possession and give it in the possession of one to whom the gift was made. If only words of Hiba are uttered, but did not give it in his possession then Hiba is invalid.
(2) It can be given according to abovementioned conditions but if Hiba is made to anyone or any stranger intending to deprive the legal heir, then the man making Hiba will be sinner because of harming heirs.
(3) Does the person have any legal witness to his claim and evidences of possessing the property in the lifetime of the parents?
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband