How to automatically have my Modpack update for others?

So I have a modded server that I'm hosting with Lilypad. I have a Modpack of only 2 mods but me and my friends have managed to get it working. I then updated the Modpack to add a third mod, and it didn't update for them. I then sent them a new link to the same Modpack and it made a separate Modpack for them and when they logged back on via CurseForge they were on a new version with the new mod obviously but their progress in the game had been reset and their settings also reset. Is there no way to have the Modpack just automatically update with new mods and not have this happen? Many thanks