Hi Elaine,
Thank you for this suggestion. Amusingly the link Pierre gave was to my exact same question three years ago, and the code from Harm works very well. In that same thread a similar idea to yours was discussed, However, I have hundreds of these throughout my ~300 page string quartet engraving and I need to have the behaviour modified globally, not for a single instance, smart though that is. So thanks anyway!
I would not call Harm's reset-beaming code code-intensive - it's remarkably short. Unless you live and breathe Scheme (as I tend to) the code is however rather hard to fathom.
Andrew