PNR vs Ticket Question

Here is my question:

Let's say i make a "Changeable" reservation for 3 passengers (all on the same PNR, but of course 3 different tickets)

And then before outbound departure i make a date change for 1 of the passengers. Would it stay as 1 Reservation/PNR for the return leg?

I am trying to be sure that my baggage allowance can be with my family on the return even if i fly to the destination without them.