Well, I (and I rarely expect much of Charlene) am surprised she isn't there. And I really hope there's a good reason because it's not an onerous engagement. Maybe she's ill - she didn't attend the Christmas Ball as far as I know and I thought she was supposed to.
As to Caroline and Stephanie - would have been great - but seems to me they're damned if they do, damned if they don't. If they turn up they're trying to steal Charlene's limelight, showing off etc. If they don't turn up and neither does Charlene then there is always someone saying they don't do anything, and if they don't then why should Charlene? (Conveniently forgetting the whole Princess Consort thing).