Worked! (on the wrong cat, though)
One of my cats suffers from stress related FLUTD and we've been using the standard Feliway on each floor of the house. Last month I tried Feliway Friends in one floor to test and it didn't seem to affect the targeted cat but the other (more independent cat) is much cuddlier than before. I will continue using it and maybe test on the other rooms as well.