Bringing up 'edit alignment geometry' should disable picking alignments other than the one picked for editing after selecting an editing option from the toolbar.
It is countless clicking on the screen currently when trying to connect alignment elements, as wrong alignment gets selected, if some element overlaps with undelaying other alignment.
You have an otpion to hide temporarily the other alignment of course, but this could be avoided I believe.
I'm still on Civil 2017, maybe this is fixed in 2018 already?