The (Bulgarian) Bisserov Sisters get about a bit. They've been performing nearly 30 years now; see this interview with Lyubimka Bisserov, who lives (or did in 2003 anyway) in the UK:

http://www.passiondiscs.co.uk/articles/lyubimka_bisserov_part_1.htm
http://www.passiondiscs.co.uk/articles/lyubimka_bisserov_part_2.htm

They have toured in Canada and the US and elsewhere. I imagine they mostly go to fairly big venues/festivals, esp when with a bunch of musicians and other family, but in their 2005 UK they (just three of them) went to smallish venues like The Topic folk club in Bradford.