In my opinion, you should just have the characters fade into the background. I.e. They're there, but they don't really do anything. Or maybe they go do something else while the people who are there adventure.
Then when they do come, just assume they were with the party all along. Don't write plot hooks for them.
It's not realistic, but it's the best compromise. Maybe try and recruit 1 or 2 additional players, so your group varies from 4-6.
Then when they do come, just assume they were with the party all along. Don't write plot hooks for them.
It's not realistic, but it's the best compromise. Maybe try and recruit 1 or 2 additional players, so your group varies from 4-6.