Well it is only your problem when it affects you. If D13 comes to you and asks for help on this. Then its your problem. The rest should be left between wife and sil. I would treat it as a non issue and continue to make sure you meet your commitments to any agreements and to your children on your time with them.
It's part of that Mr. Fix-it that you need to work on.
Kind of like the candy question.
The candy should be a non issue. As it is an issue with bad behavior. Candy should not be a reward for normal behavior, nor denied for bad behavior. Remove it from the equation.
Notice what your daughter is doing when she is being bad. Notice if there are any patterns. Teach her that emotional manipulation does not work.
Flowers always make people better, happier, and more helpful; they are sunshine, food and medicine for the soul. unconditional love is awesome!
