It is not currently possible to allocate an office credit in part settlement of an unbilled disbursement.
If you are needing to allocate a part payment, please follow the steps below:
From the DPS FD home screen, select Client Postings.
Select Bills.
Enter Matter Ref, then select Select Disbs.
Select the Disbursement and the Office Credit, then click OK.
Post Bill.
The bill will allocate the part payment, and leave a residual bill balance due.