Without know all of the details...perhaps you can suggest that your daughter tough it out until the kids are 18. This is the heart of Dr. Laura’s article here.
Divorce really hurts kids. Just because her husband “bickers” doesn’t mean she has to. And I bet that there are many things your daughter could do that would get the fella to stop bickering.
Men are very easy to keep happy if a woman really tries.
It’s far more complicated. My daughter is 4 months pregnant and has been diagnosed with cancer. His lack of compassion (more focused on how she can support him) is beyond troubling.