an alternate title "How to resync devices."
Currently, there seems to be a issue with devices that weren't successfully unlinked (happened to me recently) or devices that had the OS crash and wasn't able to unlink them prior to the crash.
SO, I propose a new feature that can re-link the existing devices all at once which effectively un-links the lost devices and forever bans them from the devices list.
The basic function would be that on an active device you can have an option to re-link simultaneously all the active devices. Basically doing the manual steps of 1) unlink all your devices, and 2) relink them one-by-one automagically in the background. In theory the manual steps aren't an issue, but if you have more than [any number greater than 2] devices... you are going to have a hard time.
My OCD gets me anxious seeing umpteen devices in my device list that haven't been active for months because I can't manually unlink them due to hard drive crash or some weird BTSync bug that forced me to re-link them without unlinking them.
Just my 2 cents.