There are a few expressions that I use on a regular basis in my home, with the girls.
That's enough squabbling. Is a popular one
Is that a nice way to ask? Is another.
I realised yesterday that there's one that I say a lot in various forms when baking, be it bread or cakes, which we do a lot. It's a long expression and it goes something like this Now you know that I don't mind you licking the spoon/knife/bowl but I've said before, we don't lick until we've finished otherwise it's like you're licking my piece of cake.
Of course I don't really mind when it's my piece that's being licked, which it most often is, but you know we parents are here to set an example, albeit a shaky one!
Hazelnut cake recipe from here.