Hugs, Tigerle! I know how challenging this situation is (x1 at least. All three? umm, triple hugs, I guess?) I wish I had something helpful to say, but I've never found anything suggesting there is something you can usefully do about tics, especially in younger kids. Everything I read suggested that even mentioning them to kids less than teens was more likely to exacerbate than help. sigh.
Once they're teen-ish, there are ways to work with them to carefully build awareness of what they are doing and strategies to control it a bit more - but it's often moot, since most kids do seem to start growing out of them on their own by then. So unfortunately, the only thing left amenable to control in this scenario is your own tic of asking them to stop. Maybe thinking of it as such will help? :P
