How to adjust pending unpaid amount of prepayment Invoice

Hi Guru's

I have a Issue where we raised Prepayment Invoice worth AED-3800000 & we have paid AED 1,986,148. Now we don't want to pay remaining amount AED-1,986,148 & we want to adjust the remaining amount with a debit memo & want to apply that debit memo to that prepayment Invoice so that balance gets adjusted. but it throws an Error : APP-SQLAP-10153: you cannot apply a prepayment to a debit/credit memo.

Note: Here we dont want to cancel the already paid amount worth AED-AED 1,986,148. Our requirement is to adjust the current un-paid amount of prepayment invoice with out cancelling the present prepayment invoice