Assalam O Alliqum
My Uncle (elder to my father) is having no child and he has adopted a girl and upbringing her. His almost all property is gifted to her by him. I have listened that it is not (gift of property) is allowed in Islam.
What would be the proper way of distribution of his property (May Allah grant him my life as well) but i would like to confirm Islam's verdict on this as my aunty too don't allow us to enter even his home and to meet.
Please eloborate
JazakAllah

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

We have already issued Fatwa 82371 clarifying that adoption is forbidden and that being kind towards the child (an orphan or else) is a good act for which the person will be rewarded if he seeks the reward of Allaah by it. Allaah Says (what means): {So whosoever does good equal to the weight of an atom (or a small ant), shall see it. And whosoever does evil equal to the weight of an atom (or a small ant), shall see it.}[Quran 99:7-8]

Therefore, this girl should be traced back to her real father and she is not a Mahram to your uncle or to his brothers.

Moreover, you should know that adoption does not prevent this gift from being valid if it fulfils the conditions for its validity, for example, if your uncle had gifted something to this girl when he was in good health and she possessed the gifted item, like him leaving the matter to her - or whoever acts on her behalf – to dispose of it as its owner. But if some of these conditions are not met, then it is a void gift. However, it is not permissible to divide anything from your uncle’s property while he is still alive except with his permission. If he dies, it should be divided on his heirs according to their legal share.

Furthermore, it is not permissible for the wife of your uncle to prevent you from entering his house or from meeting him except if she has a sound reason for doing so, because by doing so, she helps you cut ties with kinship. Allaah Says (what means): {Help you one another in virtue, righteousness and piety but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment.}[Quran 5:2]

Allaah Knows best.