vRA 6.2 Property Dictionary - Multiple relationships?

Does anybody know of a way that I can base the values in a drop down on TWO or more parent fields? All the examples I see are "Set possible networks based on environment", which is a 1-1 relationship. I need a 2+ to 1 relationship.

What I need is "Set possible networks based on environment AND application tier"

For example:

Prod

     Database tier

          Option A

          Option B

     Application tier

          Option C

          Option D

Nonprod

     Database tier

          Option E

     Application tier

          Option F

I've tried comma-delimiting the Relationship field, like you would with ValueList, but that didn't work. I tried adding additional "FilterName"/"FilterValue" pairs in the "PropertyValue" XML tags, but that didn't work either. Any suggestions?

I'm very familiar with vCenter Orchestrator, so I don't mind if the solution requires the extensibility plugin or something of that sort.

Thanks!