How to field action app link from a subtable to a Relationship Tree

Is it possible to add a field action app link on a subtable field to a Relationship Tree and filter the Tree Region Search?

In the mapper, there is no way to drill further to get to the field on the subtable to map, only the subtable data item iteself.

In the data mapper, on the from side, you should be able to choose subtable as one of the options to be able to drill down into your subtable fields