>>535084261
The main thing to make sure they're all snappable is define a size, and make sure they all have those coordinates (mine are 48x48). To have them align I mainly did trial and error - it was a bit annoying, but it wasn't too long and it's a 1-time thing (and I only have 6 blueprints in the book - straight, curve, T, +, U, and roboports)
I paste the roboports separately, but they're on the same grid and never overlap with the rails.
It took time for me to make (it was basically all I did on the first day of 2.0, remaking these rails), and you may make some mistakes with signals, but it's so insanely nice to have once you do it.