TL;DR
When you select a signal for copying or destruction the rail-parts, that “belong” to this signal should also be selected.1. When you select a rail-signal, the adjacent (two or more) rail pieces are also selected.
2. When you select all adjacent rail pieces, the rail signal is also selected.
3. Pasting blueprints has a mode, to NOT paste rail-signals.
What?
I makes no sense to copy/paste only signals.And when thinking about it, it would make much more sense to select also the two rail-parts, that are the part of the two blocks, that a signal belongs to. The pieces, that are adjacent to the signal.
That makes sense also vice versa: if you destroy all adjacent rail-pieces with a signal, the signal is also removed. Would spare me some clicks.
So, when your selection includes the signal but not all adjacent rail-pices, nothing is changed. The selection is not magic in that case.
And additionally I would say, we need then an option to paste rails with or without copied signals. Because the signals are now selected, when you select only the rails. So I suggest an option in the blueprint to not paste rail-signals. No need to remove unused rail signals afterwards.
Why?
Coming from viewtopic.php?f=6&t=93648 Auto rotate signals even when placed as ghostsThat showed me, that the copying of signals is something, that always disturbed me somehow.