Are the questioner and her sisters sinful because of their father's severance of ties with them and his not asking about them, and to what extent will his prayer against them be answered?

Allah has burdened the father with the responsibility of raising, educating, and disciplining his children, and providing for them. It is not permissible for him to supplicate against his child unjustly, for Allah does not answer an unjust supplication. As for the wife whose rights he has not fulfilled, she may refer her case to someone who will give her justice against him, or decree a divorce for her.