Also, if you think your cats would take to really stretchy collars, I use on on Oscar, and take the Feliway every morning, shake it a bit, and give the collar itself a squirt (I don't push really quickly on the spray button, needless to say).

My vet loves this "Feliway Collar" idea, particularly since it means Oscar gets the 4-hour exposure that is recommended.

The first couple of days were a bit awkward, but now I do it as Oscar is crunching his breakfast, and it's a routine.