Her first husband trying to reconcile after she married another
12-2-2013 | IslamWeb
Question:
My sister In law is in a very tense situation and it seems nobody can give the right answer. She was married to a man 9 years ago and have a 8 year old daughter. He never was religious and never worked. 2 years ago he started talking to another woman and it caused problems In there marriage and he left the house, after she talked to him and they reconciled. Months later he left and reconciled again. Then the third time he served her divorce papers and left the country to be with her without telling his 1st wife. It was a shock for us. He does not support his daughter. Now 1 year later she re-married and is 6 months pregnant and he keeps sending a SMS saying he wants to reconcile and if she wants to marry again she needs talaq fom him but she is very happy and he had already ended the relationship by Legal divorce and continuous betrayal and is pregnant with a baby.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
If that woman has married another man, then when her first husband urges her to seek divorce he is committing a grave sin because it is a form of spoiling the relationship between her and her husband and it was narrated on the authority of Abu Hurayrah 
that the Prophet, sallallaahu ‘alayhi wa sallam, said: "Anyone who incites a woman against her husband is not one of us." [Abu Daawood]
Accordingly, he has to stop doing that and it is not permissible for him to send messages to her except for a necessity because he has become a non-Mahram to her. For more benefit, please refer to Fatwa 92056.
If she is happy with her husband, then this is indeed what is Islamically required, and she should stay with him and have a good marital relationship with him and not care about the evil whispers of her first husband.
As for the girl, if she is poor, then it is obligatory upon her father to spend on her and it is not permissible for him to neglect her and whoever spends on her with the intention of asking him to reimburse him/her for the expenses that were spent, then he/she may do so. For more benefit, please refer to Fatwa 186473.
Allaah Knows best.