I sent documentation to support staff. The split and merge function you are referring to, I have already explored.
The merge function only takes two documents and places them together. You cannot control where you merge them.
If you have a large document and want to insert page(s) in various places you could achieve this using the split and merge. I've tested this.
It's impractical and cumbersome. If this is the solution, I may ask for my money back and searching another product.
I have had great experiences with many of NCH software products. I recommend them all the time.
We'll wait and see what software support comes back with. I will update once I get more information.