Revolving repayment and disbursement obligation

Dear Gurus,

I am having situation as below in SAP Loans Management.

I have 1 revolving contract with amount $10,000.00. Now user wants to key in revolving repayment due $1000.00 in SAP. By right they have to put in the conditions and post planned records using FNM1.

By right, disbursment obligation is still $0.00 but now after post planned records, disbursement obligation become $1,000.00 even there is no payment received.Users just key in repayment due.

Can anybody help on how to configure so that disbursement obligation will not increase?

Thanks