I'm leaning toward Amy being involved completely.
From all the reading, Amy had been friends with Casey for a while, so has Morales.
I think about when I was a teen/early 20's. I thought I was grown and didn't want my parents telling me what to do either. But when my parents made me mad, you bet my best friends knew it.
Her friends seem to oblivious to Caylee, for them to all talk about getting together with her and her daughter, going places together, talking about what a beautiful little girl she is, etc... friends comment on how much fun they had the day before with Casey and Caylee and can't wait to do it again..
It doesn't wash that they would just blow it off when Casey said Caylee was at the nanny's 24/7, especially if Casey was living with Amy. Where on earth did Amy think Caylee was at bedtime... all through the night... morning.... then all day?