If I’ve booked 3 people for Test Track, and we meet up with a fourth friend who doesn’t have it booked… and DW doesn’t want to go on Test Track, would it create a problem if she slipped the friend her Magic Band temporarily just for this ride?
I have visions of a Cast Member looking at the screen when we run our bands through, and noticing that he doesn’t look like a Michelle, and being in violation of Terms of Agreement, with who knows what kind of repercussions.
This happens all. The. Time. Not a big deal in the slightest. Have fun!
We’ve done it numerous times. My mom doesn’t ride the mountains, so one of us will use her band to ride twice.
This will be a non-issue 
Just to ask a further question to see where the line is drawn, suppose we have a FP+ for DD, but she refuses to ride (which she will). We meet someone who could use the FP+. Will they let her scan them in without actually loaning the band?
Hmmmm…I doubt I would do that.
I doubt I would either, just curious where they would draw the line.
Although, you would be in line with them, so maybe not a big deal. But TT has single rider, so there would need to be someone who wanted it and had others with them who already had it.
In the FP lines you need to scan twice typically. Once to enter the attraction & once when the FP line dumps into the line with the “normals”. If you weren’t giving them the band, that 2nd scan would be a problem & likely get them kicked out of the line then I’d presume as DIS CM could presume they were line jumping…
Damavs, thanks for the excellent info.