How to convert an object to a "prefab"?

I don’t see it either. There are 2 ways that I know of to do it.

  1. select everything you need and in property window look for blueprint->replace with composited blueprint. You’ll be able to edit placement of everything inside blueprint after you do this.

  2. create a new blueprint (probably actor based) and import your elements that way. You position them in blueprint editor (or with blueprint code)