Regarding gift deed from a brother to a sister

Hi , father had a piece of land which is self earned land , and he has a 2 childern i,e beother and a sister, by the time of construction both brother and sister has an oral agreement that in 3 floors one floor will give to his sister and they can use that floor and now father has transfered his property as a gift to his son , now sister is asking for floor and a land also 1/3share and want it as a gift deed which is not agreed by the time of construction now she is demanding for the registration , is there any other alternate available bz at the time of constraction they dint speak about proper registration , they just asked for an agreement . And the talk about is also about one floor not land now is there any option we can give an alternative agreement and if in case we do gift it her and register in her name only foor we can mention? Or land also (which is not said at the time of agreement) and can we make a condition that even if we do registration they cannot sell the property