You can compare up to four hive scales on one graph. Below is an example.
1.) First select the "Compare" button of one of the hives.
Notice the Compare List gets added with the selected Hive Monitor on the list.
2.) Next select the "Compare button of another hive. You will notice that it gets added to the Compare List.
Notice that the second hive monitor got added to the Compare List.
3.) Keep adding hive monitors to the Compare list. When you are ready to view the combined graph, simply press the Compare button located in the window of the Compare List.
4.) Voilà! Notice that the color coding matches the colors given next to the serial number on the Compare list.