The Offset Multiple Isometric command is used to stretch multiple sections of an isometric diagram without making changes to actual distances or elevations on the plan view.
To offset multiple parts of an isometric diagram, go to
Ribbon: DM Plumbing->Isometrics-> 
Offset Multiple Isometric
Pulldown Menu: DM Plumbing->Isometrics->Offset Multiple Isometric
You will be prompted to identify one or more isometric pipes to be offset.
Select isometric pipes to offset:
You will then be prompted to identify the location to which the pipes will be offset.
Specify base point:
Specify second point:
The selected pipes will be moved on the isometric diagram. Pipes connected to the selected pipes will be stretched to stay connected.