The system attempts to replace group instances that are from the same family table and to replace groups that are not members of the same table or that do not have a defined table.

If the existing group has the same references and prompts (such as edge-left edge, surface-place surface, and axis-axis), as the replacement group , then the groups are replaced.

If the existing and replacement groups have different references and prompts then the groups cannot be replaced. For example, if the existing group has the references and prompts edge-right and surface-left, and the replacement group has edge-right and edge-left, you cannot replace the groups.