I have two lookup fields in one form:

Lookup 1: Services

Lookup 2: Activities

When these are single-select lookups I can set the filter so that the menu of activities is dependent on the service selected.

However, when these are multi-select lookups the same filter does not work. 

i.e. on activities lookup ((Service.ID == input.Services))

Is it possible to set filter to multi-select lookups so that all services selected display all activities related to those services?

Thanks!

Lindsay