Enable locking of pipe numbers
One of the aims of BIM is that all the different models you create match. If you issue a pipe network 3D model for construction with certain pipe numbering and then a minor change happens this can affect every pipe number in the system. But once it's already been issued for construction you can't afford to change pipe numbers as it would be too confusing, which means that the 3D model can no longer match the Microdrainage model.

Thank you for the suggestion and thanks to those who commented and voted.
I am please to advise that we've successfully implemented this feature in our latest drainage design software (InfoDrainage), please feel free to download a trial and let us know how you get on.