The Edit Cable Tray Branch command is used to edit a run of connected cable trays. All of the sections of cable tray that are connected to the section you select will be modified.
To edit all of the cable trays in a connected branch, go to
Ribbon: DM Electrical->3D-BIM-> 
Edit Cable Tray Branch
Pulldown Menu: DM Electrical->Cable Tray->Edit Cable Tray Branch
You will be prompted to select a single cable tray.
Select cable tray in branch to edit:
The Edit Multiple Cable Trays dialog box will appear.
Edit Multiple Cable Trays Dialog Box
Changes can be made to the cable trays in the same way as when they were inserted. See the Insert Cable Tray section for more information.