My last handful was like that. He came here 2-3 days a week and stayed home with mom the other days. She said if he didn't get down for nap around 11 than he wouldn't at all. I told her multiple times that wouldn't work here and gave her my schedule. They, IMO, never did try to do it this way at home. I don't think she really cared tbh. He went to bed early, 630-7, was up early with them, napped at 11 for a couple of hours and I think they enjoyed that schedule.

Thankfully he would play quietly in his playpen for the most part. He would nap for 30 mins or so some days.....some days he would kick his playpen, scream and cry and cause such a ruckus that I'd have to get him. He was my only "problem napper" so it wasn't a big deal most days but it would have been much nicer had he napped...some afternoons were brutal with him because he was tired and cranky!

I suggest asking mom to get her on the same schedule as you and see if that helps!