My daughter is overweight and I am not getting any support from her father or his family on the issue.?

They see and know there is a problem. They choose to do nothing about it, and nothing you do will "make" them see anything. The sad thing here is that their continued enabling of her to indulge in unhealthy lifestyle doesn't amount to child abuse or neglect, so complaining to the court probably won't do you any good. All you can really do is encourage your daughter to make good decisions and live healthy despite what the other bad influences are in her life.