Prepayment SLA rules - unable to override segment rules

Summary:

Need to override segment rules for prepaid expense accounting entry

Content (required):

I am trying to override segment rules for a custom Prepayment Application Accrual Basis JERS but it doesn't seem possible - all segment rules are grayed out. It's an issue since the primary balancing segment is dependent on distribution line for all accounting entries except for this Prepaid expense line - is there any other way to override it to balance all accounting entries?

Thank you!

Version (include the version you are using, if applicable):

23A

Code Snippet (add any code snippets that support your topic, if applicable):