Position Mgmt: Is it possible for a current employee to apply to a job req tied to current position

This may be an odd ask, as I understand the current limitations with Oracle. However, I'm still asking. We have a project team who would like to reduce the number of positions per job code down to one, ideally. However, we have a lot of employees who change FTE within the same job code (but currently they switch to different positions). Example: a full time 0.9 FTE drops down to 0.2 FTE or vice versa.

We know there is a way to attach a current employee to a req tied to their current position, create an offer and move to HR, but then the system errors and will not allow the offer to process, so the assignment/status change doesn't go through. Is there any way for the system to be modified/configured to allow us to successfully process an offer on the same position, but that just their hours/FTE status is changing? We would love to keep everything in Oracle, but the limitations with position management have us stopped.