What I was think is to have a setting where if you enable it you could assign teams or a single server wide team where everyone on that one team could contribute to unlocking skills so if one person went off and grinded a lot of xp they could dump it all into attack and get it to level 10 everyone on the same team would also have there skill level changed to level 10 this would be useful for team events or if two friends want to play together so they both don't have to grind to be the same level It would also be nice to have a command/button to add people to your team and to lock and assign teams if your an admin.

I believe this mod https://www.curseforge.com/minecraft/mc-mods/together-forever adds that support