Question Summary:
Who is responsible to maintain my step daughter’s child if her ex-husband refuses?

Question Detail:

I am married and don’t have any children. My wife has a daughter from her previous marriage.  My step daughter was married and is now divorced with a child.
1.      Whose responsibility is it to maintain the child of my step daughter since her ex-husband doesn’t provide any maintenance and refuses to?
2.      What would happen if my wife passes away or if we get divorced (Allāh forbid)?  Do I still remain Mahram to my step daughter?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
 
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
 
If the child has his own money, then his expenses will be fulfilled through his own wealth.[1] Otherwise, it is the father’s responsibility to provide maintenance for his male child until he is able to provide for himself and for his female child until she is married regardless of whether the child is living with the father or mother. [2] This is solely upon the father and no one will share the responsibility. [3] If the father refuses to provide for his child, legal action may be taken. 
 
In the meantime, if the mother maintains the child, she has the right to demand her money back from the child’s father after legal action. [4]
 
If one consummates his Nikāh with his wife, then he is a Mahram to his step-daughter. [5]  This ruling stands even if one’s wife passes away or the marriage is terminated. 
 
 
And Allah Ta’āla Knows Best
Mawlana Abdul Azīm bin Abdur Rahman,
Student Darul Iftaa
US
 
Checked and Approved by,
Mufti Ebrahim Desai.
www.daruliftaa.net