Certain groups do not appear when Ribbons are displayed or if you choose to Show Groups in the messages window.
Modified groups will not appear in the Show Groups messages windows or if you choose to display ribbons. Until we fix this problem, you will need to define the modified group as a new group in Chem3D.
1. Select the modified group with the arrow tool. Make sure every atom in the modified group is selected.
2. From the object menu, choose Define Group. Give the group a name and a color (click on the appropriate fields).