Those look like they're going to be 'fun' to remove. Hopefully you get lucky. Douse the others in penetrating fluid for a few days (give them a few squirts as time goes on) and use line wrenches ...if they'll fit.
If I was doing it, I would remove the leaking line first. Then *carefully* inspect the actual flair to see if it's hairline-cracked. It's a double-flare in steel and steel doesn't really like to be double-flared. They often crack, sometimes they are ok but leak later on. And if ya overtighten new lines that can crack them as well. It's not an uncommon situation. There could also have been a piece of micro-grit under the line when it was installed. It was good at first, but now is leaking. If any of these are the case, then most likely just the affected line can be replaced. There might not be anything wrong with the junction block. The worst case scenario is you damage other lines during the attempted removal process. So the less you disturb ....
You'll probably need to run it through the 'bleed' process via a scan tool when you get it all back together to get firm pedal again. Might as well flush the entire system of old fluid. Your pedal will likely feel 'firmer' afterwards.
Good luck on the project.