There is no other way. The Merge LOP is how this is done. The Fetch LOP can grab the LOP contents from another node, but only one node. However if your concern is simply network "cleanliness" in that you don't want long wires traversing all over your network, or you want to access LOP nodes in a different (sub)network, you can just put down a bunch of Fetch LOPs and feed them all into a Merge.
Thank you! I am sorry I was unclear. I wanted to say that I have to find another way to organize and filter my (quite simple, freelancer's) scenes. I still have some idea of "folders" or "tags". Those primitive patterns should help. USD feels like learning Houdini once again but I like it, thank you for the great work on Solaris!