Wondering if anyone can help/advise?

[ilovetea]

My ex was ordered by the court (consent order) to pay the mortgage on our property until point of sale. He has stopped doing this and I am drafting up a charge on our property so that when it is sold I can reclaim my money that I am now paying. On the form it asks how much the charge is for but I do not know the end sum as interest rates and service charges go up and down. I will be paying the mortgage for the next few years as he is refusing to pay it. so would it be ok to make a rough estimate? Also can I charge interest on it? as I am now not able to put this money in a savings account.

Thank you for reading,