Csa and Mortgages

My partner and i live together and he pays half the rent here however he is seperated from his wife (not on paper) and has 2 children with her of which he pays a arrangement of £350 a month, they also have a mortgage and apparently after seeking advice she has advised he has to pay the full mortgage as well as csa which would after paying rent for living with me leave him with nothing?

does paying the mortgage count as CSA? they havent gone directly through csa as she doesnt want to..

what options do they have as ideally we dont want to distrupt the childrens home any more than we have already

mortgage payments, if paid on a house that the person doing the paying no longer has an interest in (and that's the key to this) can be counted as child maintenance but he would have to involve the CSA to achieve this. However, if it's a jointly owned house this doesn't count and his only legal obligation will be to pay child maintenance at CSA rates.

However, you do have to bear in mind the issue of credit ratings and the long term effects of missing mortgage payments which, in a worst case scenario, could lead to the repossession of the marital home. He would be advised to do his best to come to an arrangement with his ex about this but as long as he's on the mortgage and owns the house, he will be answerable to the lender and his credit rating! Asking for a payment holiday and going interest only are options for reducing his outgoings in the short term whilst a divorce and financial settlement are sorted.