When characters meets up again after splitting the party, it's technically necessary to fill each other in on what's happened to each group while away from the others. Of course, in reality the players of both subgroups will usually be aware of what the others got up to.
Unless you go to the bother of physically splitting the players up and enforcing quarantine of information. This is a hassle to do - but then the hassle of bringing each other up to speed on what they've been doing is such a hassle that your players might learn the lesson and not split up again.
Lando: I hope we don't run into any more troopers. Everyone knows Vader's personal guard are crack shots.
GM: R2, you see Princess and Chewbacca running past.
R2-D2: I didn't abandon Luke! I was just taking a long cut to come around from the other side, not to get around a door that I totally could have hacked open, if I wanted to.
[SFX]: < doop boop oowoo-ting doip doop bebioo ziku-ting bibuzz boop oodoo-dooby boodit-ting-pow doop boppity-bleep bap-jing whir >
R2-D2: Anyway, I've got stuff on my mind.
[SFX]: < doop bebop >
C-3PO: Well that makes perfect sense. And it's bad to see you.
R2-D2: Chewbacca, what have you done to Threepio? She's talking opposites.
[SFX]: < ziku-befiku-doip bloop-beep doop-doip ping pating oodoo >
C-3PO: No I'm not!
R2-D2: See what I mean?
[SFX]: < bop doop pating ping >
Leia: Oh... is that what was going on?
Chewbacca: Quick catch up: Vader's here. Han and I were traitors, but we're repentant now. Except he's frozen and being taken by some bounty hunter and we're rescuing him.
R2-D2: Same old, same old, then.
[SFX]: < oofloo oofloo >