I have a 4 year old goddaughter lives in another state, but I visit her every one to two months and when I visit I am often her primary/only care giver for the days I'm visiting, as her parents take the opportunity to catch up on work or alone time and I honestly prefer to get every moment I can with her during my visits.
She is a strong willed child who is not afraid to make her desires known, and as such she takes a bit of work to corral; but she is mostly not a problem with me. The worst problem I have is with her testing boundaries when I tell her not to do something by trying similar things to see rather or not she gets scolded for it (I'm working on expressing that she should ask about the other things she wants to try before just doing them). I don't get crying too often, and usually only when I've decided to push an issue to teach her a lesson about discipline; and I almost never get a full blow temper tantrum.
Her mother however says that she seems to have more temper tantrums right after my visits. I've also noticed when her mother and I take the child out together near the end of our visits my goddaughter seems far worse, with more temper tantrums and general crying.
I feel as if the issue may be a difference in 'parenting' styles, if I can call it that when I'm not actually a parent. While I wouldn't say we are completely different in child rearing in general I would say that I tend to have less rules then her mother, but I'm also stricter on enforcing the ones I set, ie there is plenty she gets to do and decide, but when I tell her something I mean it and she has to listen to it. Her mother tends to have more rules, but is more lenient with the girls bending those rules then I am. Her mother also tends to use empty threats, which I don't personally like to see. With me I only threaten a repercussion for bad behavior if I intend to follow through with it; even if following through with it proves to be inconvenient or gets in the way of planned activities (which is why I'm also more cautious about making such threats).
I think my goddaughter may get confused when going from me and my sorts of rules back to her mother's rules after I've been the primary one caring for her for a few days, and especially confused when were doing something together and there are two sets of expectations (though I mostly try to yield to her mother's rules and expectations when were together, she is the parent after all).
She also tends to not get quite as much sleep as I would prefer when i visit, as she doesn't want to nap when she could be playing with me, and since we often go out somewhere nap's aren't always as easy to arrange. She doesn't need to nap all the time, but since we usually do group activities in the evenings after her mother's job that means she is at her most tired, and thus most prone to tantrums, when we are doing group activities. When we don't do group activities and I just have her all evening by myself she still does well without naps.
Is there anything I can do to help her with transiting between our two styles, or minimize the tendency for her to get upset and have temper tantrums when we take her out as a group to do fun activities?