Receivable question - direct journal an OA (on account) payment

Hi,

I'm looking for some help in the following scenario:

- A payment of 10k is received as an advance for a grant (prepaid). It has been applied to the invoice

- Final utilization 'exhaust' only $9,500 leaving in deferred revenue $500.00

- A credit invoice for $500 is created and via MT Worksheet unpost and partial post is performed

- Now I'm left with $500 open item (it can be placed on OA)

- Sponsor (customer) does not want a refund but allows institution to keep it for further research. Therefore, this amount needs to be distributed to a departmental account as a residual balance.

Is there any work around to achieve this without the need of manual online journal? It could be great if the $500 can be direct journalled.