I am trying to set Service Activities to allow me to select from a Category Lookup field then Select a Service from the default Services Field. The Services field should be filtered based on the selection from the Category lookup. I have seen information about how to perform filtering but it seems there is always a way to relate the two fields. I cannot add any fields to the services entity to relate them so not sure how to do this.
Example:
Category1 is Chosen, display Service1, Service2, Service3.
Category2 is chosen, display Service 3, Service4.