Nothing! Absolutely nothing! DD just said - "OK, I'll see you later in the week, then". That was it - no tears, no tantrums, nothing! The result - I had a lovely day with my mum, and will be seeing dd later in the week - everyone's happy. So, what did I learn today? That sometimes, you have to say NO, just grit your teeth, take a deep breath, and say it!
I then got to wondering, how much more peaceful my life might have been had I learned this particular lesson a lot earlier!! I haven't quite finished the layout yet - I haven't quite decided on the wording for this lesson, but will add it when I sort it out.