Two Filters from One Slicer

I'm trying to use a date slicer to ultimately filter a fact table where each row represents an event, but the logic is tricky and relies on a helper table. The date slicer has a granularity of selecting months or years, no quarters or days.

Fact/event table columns: DeviceId, EventDate, EventMonth (same as EventDate but the 1st of the month)

Helper table columns: DeviceId, EligibilityMonth (date that is the 1st of the month)

Desired filter logic:

1. Only rows with EventDate within the month(s) selected

2. Only rows with DeviceIds that are eligible in ALL the month(s) selected

1 is easy on its own. 2 is a little trickier, but I've found guides for making a slicer do AND logic rather than OR with the selected values (one guide). Where I'm stuck is combining the two parts of filter logic at the same time. I think this is doable if I had two date slicers, but that's not ideal, and would require some way to ensure the user selects the same month(s) in both. Any suggestions?

What I've tried: Making two relationships between the fact/event table and helper table, DeviceId to DeviceId and EventMonth to EligibilityMonth. However, Power BI limits me to one active relationship.