Can i extend AProceduralFoliageVolume to work runtime??

Am having some trouble extending AProceduralFoliageVolume:: so I can use it runtime.
First off is this possible?

First issue I experienced was when I have extended the foliage volume it dont work as before. The brush is not updating so it says I dont have large enough space to spawn foliage.

Anyone have any ideas on how this can be done?