Why was McGee's You Meddling Kids line directed at the Casagrandes rather than the sisters when the latter pair mainly tried to stop him? Because he had an army of hypnotized pre-teens who would've overwhelmed the Loud sisters and thus eliminate them as a threat. The Casagrandes came to the rescue by flinging Rosa's cuisine at the zombified kids and therefore ruin McGee's scheme.
To be fair though, he does call the girls 'meddlesome' at one point.
If the Casagrandes went to an improv club, how come they didn't try to get Ronnie Anne to come with them? Maybe it was because she told them beforehand she didn't want to go and that the Louds to watch her while they were away.
If Rosa goes nowhere without her cuisine, how was she permitted to bring it in the improv club?