I don't want PSG and RM in the same group.
Though if they finish 1 and 2 would that put them on opposite sides of the bracket? Too lazy to look it all up.
Only group stage limitations are that you can't have two teams from same association in the same group.
In R16, the group winners are the seeded teams, and 2nd place are unseeded. Seeded teams are drawn against unseeded teams, but same association teams can't be drawn against each other nor can same group teams.
In the QFs any same association restrictions are done and there's no more seeding.
That would mean if PSG and RM are in the same group they couldn't meet again until the QFs