Why could Rapunzel's tears heal the prince's blindness? What happened to the maidservant after she and Maid Maleen got their jobs at the castle? What happened to the king in Rumpelstiltskin -- did he, after marrying the heroine for her ability to spin straw into gold, never demand that she do it again?
So -- you have to patch them up. Characters who vanish have to be given reasons. Characters who do things that would produce ripple effects should see ripple effects. And things that they stop doing -- or that they have to pass on to someone else to keep doing.
(Assuming, of course, you don't just rip off The Three Aunts instead of Rumpelstiltskin.)
But if you have an innkeeper whose inn is in the middle of nowhere, not even a small village about, and it's all the innkeeper's family, and they want to leave. . . .
I go hunting about for a fairy tale with more innkeepers to fix it up. Which is not so common as princes, or farmers, or even soldiers or tailors. But it's better than -- oh, a map-maker or a wheelwright.