As far as I understood (and also as it is implementer in Glassfrog) you don't just merge two roles or two circles. Instead you:
- remove existing roles (circles);
- create new role (circle) with a new purpose;
- add need accrountabilities (roles) to this circle;
As far as you see circles as simply roles from a point of super-circle, then you should merge them also on super-circle Governance meeting.