In that case, you can enter trumpets 2–4 using cues from trumpet 1. They’ll be linked to trumpet 1, so any changes will automatically apply to trumpets 2–4.
As for the lines, you can enter them in the full score and make them transparent in the parts — they won’t be visible there.
(But this involves certain cue settings (note size, hiding rests, etc.) that might be a problem elsewhere in your project if you also want to use “real” cues.)