Prepayment p0411 and p0413m

Dear ,

i use jde 9.1.5 i have this scenario:

1. i enter prepayment 1000 using p0411

2. i entered actual expenses voucher 500

3. when i use p0411p to match the system will give error and the only way to match is by making negative payment.

4. when making negative payment this will close the prepayment voucher however i dont need to close the remaining  prepayment amount which 500

so how can i match the prepayment with actual voucher and still have the remaining prepayment opening to any next voucher in futue?

another question?

how can i use split payment option in p0411p and is this way will give me the needed result?