So I know there are already many threads about the woes of PNR splitting... but my situation is somewhat complicated and I want to make sure I'm understanding the lay of the land correctly.

I have a roundtrip booked for 4 individuals, including myself. I'm 1k, but none of my companions are Premier. I've requested PlusPoints upgrades for all 4 pax on both outward & return. After putting in those requests, I opted to split into 2 PNRs of 2 pax each to increase the likelihood of upgrades clearing as pairs. Right now we are in slots 1-4 for the outbound flight with a few seats open, a couple days from the flight, so I think odds are good for the airport list but bad for the advance list. The return flight, on the other hand, has a ton of inventory and I like our odds there.

I understand that with instruments applied, the PNRs will automatically split again at check-in. I'm less concerned about loss of Premier benefits (i.e. luggage, boarding), but I want to make sure I don't impact our upgrade chances for the return flight. If our PNRs are split, am I correct in understanding that the other 3 travelers will no longer be next to me on the return upgrade list, but will rather drop to the bottom of the 1k section of the list? If that's the case, given odds of all 4 upgrading are good for the return, I'm thinking I should cancel my requests for the outbound and mark for no upgrades (even though an upgrade looks likely for the airport waitlist). Am I interpreting this correctly? Any thoughts/suggestions?