Asalaamalaikum
I will break this matter down very simply because it's urgent and needs to be sorted out.
A sister divorced her husband by khul and she gave him back the mahr of £500 (dowry) he gave her in return for her khul. They are now back together after about 6 months apart and are marrying again today in a new marriage contract.
The problem : the sister's friend had a husband who gave her the £500 mahr to make her life easy so she could get her khul asap. She didnt have any money as far as I know at that time to be able to pay the full mahr for the khul. Now they have got back together all of a sudden, the husband would like that money he paid for the sister, back.
Your perspectives?