Hearing that she gets grabbed like that makes a lot more sense. She's learned that hands mean getting grabbed and held in place when she doesn't want to be, and that's probably contributing a lot to her problem. The only way to permanently fix that part of the problem is to make your family understand that they can't force her into anything like that and they need to respect her space. They're only making her nervous and afraid of hands and people and she's reacting aggressively, which is perfectly reasonable to her.
Isy did do really we with other animals. I had an older cat who was about 5 when I found Isy and they were never really close but got along fine, but the big thing that helped was when I rescued my abuse survivor kitty Maya. Maya's a very quiet, timid, calm cat and Isy just took to her instantly and it helped both of them so much. In this case Maya was several years younger but with you I'd recommend looking at an older (not really old but maybe 2 years or so) cat with a calmer, gentler temperament. Try for one who has been well socialized with other animals. They could really help Nala a lot as far as teacher her to be calmer and gentler with others. But a big part of the root of your problem (I suspect) will still be the way she's handled by the other people in your home and she'll never make real solid, long-lasting progress if that doesn't get addressed.
Isy did do really we with other animals. I had an older cat who was about 5 when I found Isy and they were never really close but got along fine, but the big thing that helped was when I rescued my abuse survivor kitty Maya. Maya's a very quiet, timid, calm cat and Isy just took to her instantly and it helped both of them so much. In this case Maya was several years younger but with you I'd recommend looking at an older (not really old but maybe 2 years or so) cat with a calmer, gentler temperament. Try for one who has been well socialized with other animals. They could really help Nala a lot as far as teacher her to be calmer and gentler with others. But a big part of the root of your problem (I suspect) will still be the way she's handled by the other people in your home and she'll never make real solid, long-lasting progress if that doesn't get addressed.