Inheritance

Q: I would appreciate a brief Shariah ruling on a family property matter. 

An unmarried adult daughter occupies three commercial shops belonging to a family property, which she uses for her medical practice. Her father allowed this during his lifetime, but he also charged her rental at certain times. He has since passed away, and the property has devolved to the heirs. 

She is financially self-supporting, has her own home and other assets, but maintains that because she is an unmarried daughter, she is entitled to continue using the three commercial shops rent-free after her father's death, in addition to receiving her Islamic inheritance share. 

Is there any Shariah obligation on her brothers/co-owners to provide her with these commercial premises rent-free? Or should she pay a reasonable market-related rental for the shops like any other person occupying family-owned commercial property?

Q: After a male has passed away, does his wife, who is under iddah have any say of his affairs and who is in control of his affairs? Does his sons and his sisters have the final say, or does his widow still have a say in his estate and affairs?

Q: During the process of winding up my father’s estate, my sister accused one of the other heirs of stealing their father’s money. The said heir was very upset over this accusation. Hence, this heir forfeited their share of the inheritance in the estate.
Few years later, my sister retracted the accusation and apologized. She also stated that if it was due to her that the other heir revoked their share of inheritance, then she is ready to negotiate a way to give back that share of inheritance. This however did not materialise till this day.

Please advise if the forfeiting of the share, under the circumstances concerned, were valid and binding? If yes, who should that share be given to?

Q: There were two brothers owning a business 50% each. One brother passed away, they distributed the inheritance of the business in percentages. e.g. 10 percentage to one person, another 5 percent to another and in this way they continued to receive a profit from the business. Now, the other brother wants to forcefully buy out the other portion which belongs to the deceased brothers children and wife. 

1. Is it permissible to distribute the inheritance in this way that without dissolving the business people are giving a share? 

2. Can the brother forcefully buy the other portion of the business?