Daughter in-law problems

Q: My son got married two years back,which I was against but however he did not listen and proceded with the nikah. She is a girl that does not want to mix with the family, preventing my son from mixing with family and breaking family ties. She is troublesome and brings on petty issues that has no concrete reasoning just to bring on a fight. Her parents are very controlling in my son's marriage. Please can you give me a dua that she leaves our family to prevent further future problems and they separate.

Intending to perform nafil salaah or to keep nafil fast

Q: In the one instance, one makes intention to keep a nafil fast or to perform a nafil salaat. But then, at the appropriate time, one changes one’s mind and does not keep the fast or perform the nafil salaat. In the second instance, one had already commenced performing nafil salaat but when one’s wudhu broke, one did not renew one’s wudhu and abandoned performing the nafil salaat. In the first instance, is it now mandatory to fast and perform the nafil salaat one had intended to perform? And, in the second instance, does performing the abandoned nafil salaat also become mandatory?