Hi!
As an idea, maybe you can implement this if it is interesting.
Right now the mod completely changes the behavior of underground pipes, and they cannot interact with other underground pipes. This is not very convenient, especially if you add this mod in the middle or end of the game, because a lot is already built.
The idea is that if you add the ability to switch modes in the pipe itself, then the user will have a choice where he can specify what behavior the underground pipe should have, normal or new. For example, by default the pipe behaves as usual, but if you switch it to the second mode, then the pipes can already be intertwined and connected by colors, etc.
You can also add a button to switch the mode, as it is done on https://mods.factorio.com/mod/flow-config, so that it is easy and quick to do.