Approvals based on Position FTE/Headcount Availability

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We have a requirement to build different approval paths for job requisitions based on if the req would put the position over the budgeted FTE/Headcount or not.

Example: Position has 5 budgeted FTE. It has 4 FTE incumbants. Job Req is for 2 FTE. Approval path would take path A with an additional approver since the 2 openings on the job req plus the current 4 would  put the position over. If Job Req is for 1 FTE, approval path would take path B with fewer approvers as it's within budget.

Has anyone had a similar requirement? Recommendations on how to handle this?