My Question Is To Help My Sister Who Is 58

My question is to help my sister who is 58 and has been very underweight for 10-15 years. Her friends and children had her put in a medical (lock down) facility a few years ago, but it didn't help, because their diet gave her a fatty liver. She is always eating lots of salads and veggies, but takes in VERY little fat. She does eat "balanced" meals with protein, but she is barely more than a skeleton and her veins are exposed on arms and legs. I know her immediate family life has been very stressful over the last 20 years & has the need to control everything. So... I am hoping to give her some good suggestions for adding in more fat content without the risk of "bad fat." I know, she probably needs counseling, right? Just thought I'd try this first!