When recording or copying a group, if the destination location already has a group recorded in it, you will be prompted with record options of Insert, Merge or Replace.
If you are moving a group, only the Insert option is available.
Insert: creates a new destination group. The new group will be assigned a free location just before the one chosen, using a point number if necessary.
Merge: Incorporates the new information into the destination group.
Replace: Overwrites the group information in that destination.
If you know that you are about to record, copy or move a group to an existing destination, you can pre-select Insert, Merge or Replace from the Record Options Toolbar. This appears after you press the Record, Copy or Move keys.