Did a search, but not sure if this has been addressed prior...

I will be traveling EWR-LAS next week, I am 1K and will have a general member on the same pnr.

I know that if I use miles to upgrade the GM on the return flight then the pnr will be split.

If I wait until the outbound CPU clears for both of us, then use miles to upgrade or waitlist the gm for the return,

Will the gm lose the outbound upgrade once the pnr is split?