This filled me with terror. Doing errands with both of them is not fun, and I rather felt that Margaret would be bored with Ellie's haircut.
Luckily, Margaret's friend down the block wanted to borrow her for a bit, and so we left Margaret and went to get Ellie shorn.
She was exceptionally well-behaved. And described the haircut she wanted to the hairdresser, with an appeal to me to show said hairdresser a picture of Margaret's haircut.
So I did, and then Ellie got hers.