Indeed, the issue I noted earlier arises when the selected arcs are not in the same edit context (model, Group or Component). The attached revision accepts selections only if they are in the same context and puts the new guide points into that same context.
I considered allowing different contexts, but there are several problems with that. At a basic level, the plugin gets much more complicated because it has to deal with Transforming everything into the same coordinates. It would also no longer be clear what context the new guide points should be placed in.
SB_intersect_circles.rbz (2.4 KB)