Family Tree Script - Paid development

Hello Guys,

I will be a running a social website for a huge group of family members, who are currently present all over the world.

It will have more 5000 families registering individual family members.

1 - Every family will have a head of the family, and may also be a part of  another family

For Eg - There is a Family which has Mom, Dad, Elder brother, Younger Brother, the head of the family is Dad, Now the elder brother is married, and has a wife, and a kid, so he is the head of that family of his and is also a part of another family where he is not the head of the family and his father is the head of the family. 

2 - They would have a membership module integrated, which will just confirm that they have paid the annual membership fees, and all family members under that family are covered in that payment, payment is taken offline at this point in time, however in future we should be able to sell it online as well.

3 - There should be an option to automatically change the head of the family in case of the head of the current family is dead. For Eg - Considering the above case, if the Father is dead, then the eldest son/Mother should become the head of the family [maybe title or identify as sub head of the family]

4 - There should be a possibility available where multiple families can be merged/broken as a nuclear family. For Eg - in the above case, Eldest son can choose to stay with his father, and eldest son wife and kid would be under the Head of the Family of his father . . . . or he can choose to make it a separate  arrangement and not be a part of the family and show himself as a Head of the Family for his wife and kid. [Leaving a room to still show/not show himself as a part of his fathers family as a son.]

It would be like the Facebook family Tree, with an extra option of showing the head of the family and editing it.