Party toggle is a rather simple extension for Party and Friends (for the Extended Version for Bungeecord/Velocity and the Extended Version for Spigot as well as for the non-extended version for Bungecord and the non-extended version for Velocity). This extension adds the command /party toggle. With /party toggle, your players don't need to write always /party chat to write into the party chat. If activated, your players can just write into the normal chat to talk to their party.
Just put the jar into the plugins' folder of your Velocity/Bungeecord folder, or into the Spigot plugins folder if you are using the Spigot version of Party And Friends.