Sorry for the delay in getting back to this thread. Thanks much for answering! Recently I tried to take 2 spline based tree trunks and merge them as a test, and to my surprise, each branch with it’s accompanying foliage was 20 items, for a total of 40 assets, and when I selected merge, UEv5.1 crashed to desktop several times.
I’ve submitted a bug report to Epic, but in that report I acknowledged that I have no idea if the mechanics of pieces of spline based trees are such that they can be merged? Do you know by chance?
I will look into Level Instancing as my next quest. 