Union Set Up

Hello, We are a highly unionized organization with multiple union with different rules/deductions per union. I want to understand what is the best way to maintain union data in PeopleSoft. We had earlier set up unions under benefits (8Y plans) however, there were a lot of issues when employees moved between unions or from non-union to union position deduction were not calculated correctly.

Then we moved union set up to general deduction, we also have employees in multiple positions and one employee can be in different union. But general deduction page does not have empl_rcd hence we are having issues with union deduction again. sometimes also when we need take some back dated deductions.