Does a divorced wife have the right to child custody while she is not settled in one place (between her father's house, her brother's, and her divorced mother's, who is married to another man), and is her mother's husband a forbidden mahram to her daughter?

The divorced mother who is not married has the right to custody of her daughter until she reaches the age of discernment. If she reaches that age, she is given the choice between her parents. The mother’s custody of her daughter does not cease merely by moving between relatives’ homes as long as it is within the same country. However, if the distance between the homes is considered a journey, then the child stays with her father until her mother returns. The mother’s husband is a mahram to his wife’s daughter because she is the daughter of his stepchild.