Let's say there are 4 spans and the user defines a bridge with 5 supports and the deck and beam groups run from support 1 to support 5. Then the engineer learns that we don't want this long of a bridge, only 3 spans. Please add the ability to change the end support (or begin support) for the deck and beam groups so that these can be redefined and the 5th support can be deleted without deleting the entire superstructure.