Si j'ai bien compris :
on join:
wait 10 ticks
wipe player's sidebar
if player is "pseudo1":
set name of sidebar of player to "titre1"
set score "message1" in sidebar of player to 15
else if player is "pseudo2":
set name of sidebar of player to "titre2"
set score "message2" in sidebar of player to 15
#Tu peux en mettre autant que tu veux
else: #Tous les autres joueurs
set name of sidebar of player to "titreDefaut"
set score "messageDefaut" in sidebar of player to 15