Yes, either parent can take a child if there is no custody agreement set into place yet. The father will need to hire an attorney and fight the mother for custody in court if he thinks she is unfit.
Father or Mother
Uh, they're your mother and father. Their relationship to each other does not change their relationship to you. Your parents are your parents regardless.
Grand mother
The analogy for brother is to mother as fly is to father, as a fly typically shares a direct relationship with its environment or preferred location, similar to how a father may play a distinctive role within a family dynamic.
your grandfather
If your mother and her brother share the same parents, then her brother's father would be considered your grandfather
She is the co-mother in law of you and your daughter's father in law is your co father in law. :-)
a bad one
Second cousins.
Mother, father, sister, brother, aunt, uncle, friend.
Marriage of the mother, father or child have no relationship to the collection of a debt.
Yuor motehr-in-law is not related to you father. They would be introduced as "This is xxxx, my son's mother in law."