Funds availability - rejected parked document

For all AVC gurus,

When a parked document is created, the available funds are reduced after the document complete box is checked. But, if a parked document is rejected during the approval process, the available funds are unchanged (do not increase back to previous level).

We did not use standard FI workflow and we did not use standard FI business object FIPP for FI workflow either but it was a copy of FIPP.

Just in general, is there some setting or conditions we need to make to adjust the available funds when a parked document is rejected during the approval process?

Thanks in advance!

Regards,

Fisher Li