How to make plants only generate on assigned actor or actors with assigned material?

Hello guys. Currently, I make assigned actor that should grow plants to be saved as another Sub-Level, and then to generate plants in such sub-level. Then, the plants in persistent level can be limited to assigned actors. But such way is a little bit tedious and not intuitive since there is no reference when generate plants in sub-level.

The filters in Foliage mode also does me no favor (or maybe I have not understood it yet). How wonderful it is should filters can limit plants only be generated on assigned actor or actor with assigned material!
Or, how wonderful it is should the procedural foliage spawner have above mentioned function!