Hm... Ok, given how quirky the rails are in the game (being kinda irregular shapes and all of that in a grid-based system), I actually tried to mess around a bit with the blueprints that involve them.
So... I'll wait for you to produce the sample blueprints for me, but what I've tried is using something like this:
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And basically trying to place multiple copies of blueprint down by offsetting them horisontally (kinda like building a train stacker), while having the auto-approval disabled. Unfortunately, even force-pasting (via shift-left click) won't place all the required rails - mainly it won't let you connect to existing unapproved ghost. Technically speaking, it will complain about placeholder ghost being in the way.
If you are facing the same issue, the bad news is that this is probably not solvable with the way the mod is implemented. I'm thinking that maybe I could change something around collision layers, but... Not sure if that would work correctly (I think the placeholders have to collide with the rest of the ghosts for some good reason (tm) as well).
Best regards,
Branko