Users should be able to create a filter that references other filters. Sometimes we make filters that would rely on a base filter but have to manually enter the conditions again. This not only leads to complicated logic, but if the base filter ever needed to be updated, the logic currently needs to be updated in every filter. This idea would only require updating the base filter.
There should be a special "#Filter" property dropdown, the options "Is True" and "Is False" in the comparison dropdown. Then in the value dropdown, it should list all compatible filters. A compatible filter is one that is a superset of the categories you are currently filtering on. So if you are filtering for [Conduits, Conduit Fittings], a filter that filters [Conduits, Conduit Fittings, Cable Trays, Cable Tray Fittings] would be compatible.
This would all work in the current form factor:
