Make player cant remove party if are in X area, or if have X storage

[roriscrave]

I developed an NPC that to talk to him, you need to be partying with 2 more players (totaling 3).
After talking to the NPC, he teleports all 3 party members to an arena.
I'm doing that in this arena it will be PvP 3x3 of the party teams.
For this, I need that within this area, it is not possible to remove the party, or to invite other players within the party. How should I do this? Should it be done by LUA or C ++?
Remembering, I use TFs 1.3 8.6

 

[Evil Puncker]

you can try using the player events on party.lua

function Party:onJoin(player)
    return true
end

function Party:onLeave(player)
    return true
end

function Party:onDisband()
    return true
end