How to enable multiple assignments for benefit relationship

Summary:

We are rehiring a retiree into a non benefit eligible role. Therefore, we need to change their benefit relationship assignment to their original role they retired from as they are entitled to benefits from that role. When we try to change in the benefit relationship page, we get an error that a record with this combination of values already exists.

I have tried to enable multiple assignment processing under setup and maintenance- configure default benefits relationships, however the enable multople assignment processing field is read-only and not editable. How do I edit this information?

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