MooWaza said:
They were clearly working together as you can see in the deleted scenes of Return of the Jedi. Whether this is valid is up to you since they’re not in the final movie, but it shows the original idea when making the movie.

True. There’s also dialogue at the end of ESB that implies Luke and Lando at least are planning to meet on Tatooine. But I guess they never got around to it until 3 years later.

Before those ROTJ deleted scenes were available on Youtube, I assumed Luke and Leia/Chewie/Lando were carrying out two independent plans (coincidentally at the same time). That seemed like the only way to make any sense of the bizarre sequence of events.

So I guess Plan A was to just send Lando undercover and then send the droids to deliver Luke’s message. It’s unclear how Jabba was supposed to even communicate with Luke if Plan A worked, but whatever, maybe R2 had some comm device. So then Plan B was to send in Leia and Chewie. Leia needed Chewie to get inside the palace, but it seems that, once inside, Leia was supposed to just wait until everyone fell asleep and then unfreeze Han and sneak him out. It’s unclear how they planned to extract Chewie. Maybe that was Lando’s job? But then why couldn’t Lando just unfreeze Han and sneak him out without Leia/Chewie getting involved? Maybe they were afraid Han would react badly to Lando (who betrayed him). But that just highlights how little strategic sense it makes for Lando to even be involved in this. Boba Fett could easily recognize him, and Han probably wouldn’t trust him. Plus, Lando never actually does anything to help anyway (that we know of) until the plan has already collapsed.