If merging candidates are members of particular a group(s), remaining connectors after merging will assume group membership of all originals removed per remaining connector. That is, if “con-1” belonging to “group-1” is replaced by “con-2” in “group-2”, that will make “con-2” a new member of “group-1”.
Free connectors are used by a single domain or none.
Manifold connectors are used by two domains.
Non-Manifold connectors are used by more than two domains.
The Merge panel is used to remove coincident and overlapping connectors.