Two Unions - Only 1 Following state mandated Sick Time

Hello, trying to see if there is any advice on the best way to set up accrual for state mandated sick time only in effect for one of our unions. 

Our workers mainly work in 1 union that their CBA currently is waiving the state mandated sick and safe time. The other union we only occasionally work in came out with a statement that they will be following the state mandated sick and safe time and I received confirmation from both of the unions that if the employees work in the union that will be following the sick and safe time that we are required to accrue for those hours. 

I am not able to set up the accrual on the 5-2-1 screen under compensation because that would accrue for all hour and we only want hours to be accruing when they work in the specific union. I did research and tried to set up a pay calculation with what is listed in the Sage User Manual and do calculation type of accrued hours. It accrues accurately when I try it out but if the employee would like to use those hours I can not get it to take away hours from this. Could this be because we have to have separate payroll records for each union because if we have both unions on one payroll records the union calculations are incorrect? So if an individual did not work in the union with the state sick and safe time - to take time away it would be a negative check but they would have actually hours on a different payroll record...

Are there any other contractors out there with this sort of situation? How do you handle it? If we can't accrue and take away time accrued in Sage I will have to track it manually but I thought I would check to see if I was missing something?