HiI guess whether you play with one or two fingers between the bones is down to personal preference. I find you have more control with 2 fingers. Didn't want to suggest that one way is better than the other.
A fiddle player I know knew someone who played with four bones in one hand. Seems a bit excessive to me and definitely a mushy sound, I would imagine.
Anyway, thanks to Mike for all your interest in my Dad. I'll look forward to seeing the info I sent on the bones website.
Louisa