To add a segment to the middle of a feeder, go to
Ribbon: DM Electrical RT->Feeders-> 
Add Segment to Middle
Pulldown Menu: DM Electrical RT->Feeders->Add Segment to Middle of Feeder
You will be prompted to identify the location on the feeder where you want a segment to be added.
Select point on feeder to insert segment at:
Select the feeder where the segment is to be added. A new segment will be inserted. The appearance of the feeder will not change, but you will have new grips that you can use to drag the feeder into the correct shape.