Thank guys, as always.
She is 10 but I think the reason is she hasn't played with him like we have. When he went nutso this morning I put him on his back and held him down, looked into his eyes and told him "NO!". He squirmed like a fish but did settle down. I need to reiterate to her the correct commands, too. She will tell him "STOP!" but I say "NO!". She needs to be more assertive as well. She doesn't have a problem doing that with Jacob.
We didn't have the kids when Mack was a pup so this is new for them.