Spock's going to ask Archer if he would act as Justice of the Peace for the ceremony. I'd love to see the eyes of those stiff formal suits at Starfleet headquarters when we come up with a marriage certificate signed by Archer himself. I'll bet they'll be grilling us for details as to what Archer did, what he said...
But what if when he doesn't want to...? How to convince him...?
Screw the timeline, why shouldn't he know he's one of the Founding Fathers of the Federation? If Spock won't use that as an argument, I will.