Hey karena, welcome to the forum. If you could both keep servicing the IVA then that wouldn't be a problem, your IP would have to go through a new income and expenditure with you both as abviously things will change. As for the equity release clause, you better wait for Melanie to answer that. X
I assume that you have mutual and interlocking IVAs, where you just make one payment rather than pay individually, so if you separate you will need to get your Supervisor to either vary the terms of the arrangement to allow for individual payments, or continue to pay your share of the contribution into the future - in which case the arrangements are unaffected.