Rules regarding in game alliances/plans

I obviously know the rule about secret alliances, but i am a little foggy about plans made in the alliances. I do not want to get negative feedback becuase i messed up. My question is this. "If i have already asked for an alliance and the other accepted it, do all our plans have to be put on the chat board or can they be made with private messages" And plans refer to things like, Coordinated attacks.....Fients.........pretty much all sort of plans. I would think this would be allowed to do since the persons alliance was said, but i want to be sure