How to get refference to an by editor set staticmesh from c++?

We actually have a level containing a Blueprint with some staticmeshes as sub of it.
Now this staticmeshes should at sometime dynamicaly be altered by playerinput, what is handled from c++.
Thats the plan so far.

But I have no clou how to get reference to the placed blueprint and its content.
Currently I’m working with an empty baseclass.
Should I use scene actor or another type of actor for it?
If so, how to access a root element from there?
And how to navigate from there to my blueprint?