Well I feel if the child is in my house he still has to respect the rules regardless of weather mom or dad is there. A quick fix would be to have the child ready with their shoes on when the parent arrives. If the child complains then say" your ears dont seems to work when your mom arrives so now we do it this way. I have a child that since the beginning of time has pitched a fit the minute mom walks in, if dad picks up it's a different story. So 5 mibs before mom is due to arrive I say to the child "ok time to get our shoes on " and he goes through the gate and I shut it behind him so he can't escape and he puts his shoes on and when mom walks in he's happy. A few weeks ago mom showed up 20 mins early and he was just opening a book... well he threw the book down and started to yell no no no .... I took him thru the gate and mom put his ball cap on him and he threw it off and as she was putting his boots on he was taking them off ... So I plunked him on a chair and I said "it's time to go put your boots on now" and I shoved his boots on his feet and stood him up and mom said let's go he started to throw another fit and she picked him up and left ..... That'll teach her for coming early!!!!!