This is pointless.
I wish I had made these so that we could talk instead of only being able to write. I wonder if it could be done? I could have tried a variation on the wireless charm, perhaps, except that there'd be no way of making that private, and that would defeat the point. I can't do the wireless charm in any case, it's much too complicated. Your Gran would probably know.
Actually, speaking of your Gran, if you see this any time soon could you ask her if she knows any simple charms for blocking the Floo? Ours here is supposed to be blocked, of course--Mum did it last fall when they moved up from London--but it's been making noises and I'd like to make sure.