The
SkyTeam website has this interesting wording:
SkyTeam Elite Plus members can invite one guest who must be traveling on the same SkyTeam member-operated flight, irrespective of their preceding and any onward flight.
I can infer what they are trying to say, but it makes it sound like it doesn't matter on what flight your guest arrives or departs. Of course, the fact that it applies on the same SkyTeam member-operated flight means that the only way this should work is for your guest to be on the same onward flight as you. Or do we think that the same incoming will also be accepted?