This shouldn’t matter as far as I know.
Yes, I don’t think there should be any issue with this as long as you add the appropriate sync code to each installation it should work just fine.
Apologies but I’m confused, you’re saying that if you go to Settings --> Sync --> Leave Sync chain and click OK in the confirmation window, the Desktop device on the chain is still showing other devices? Would it be possible for you to share a short screen recording of you performing those actions so I can get a better idea of what’s happening on your end?