Lipoma on a dog.

Hi Dr. Laurie, You gave me such great advice on my cat Bobo, I'm writing about my Parents dog Pepper. Shes a spayed overweight (medium sized in height but about 80 lbs)female dog around 8 years old. She still gets around well, and when she sees a squirrell, shes like a bullett (sp). My question is, she has a soft growth about the size of a solftball, maybe a little bigger, yes I said soltball. She doesnt flinch when you rub it, push on it, play with it in any way. Doesnt seem to bother her at all. When I parents brought her to the vet he said it was just a 'fat deposit" that she was so fat or something, the fat had no where else to go, so it was just clumping in one area. This sounds hokey to me. Is that possible? Shouldnt it be removed? She refuses to go on walks and has the run of a large yard whih she prefers to stay in. Her sister , by the way, is a year or so older...golden lab / chow mix, and is in liver failure and they said theres nothing they can do at this point excxept keep her comfortable, she also has very bad hips and is on tramadol or toradol , never can remember the two, and is about to go in to gave a benign tumor removed from her eye. I hope her old body can endure the operation, although I'm pretty sure they understand she wont be with us much longer, they are determined to make her last days as good as possible. Do you think the anesthesia will affect her liver failure? I'm sure her vets are taking all precautions.
I'm not sure if asking 2 questions for 2 different dogs for one price is fair,I know this takes a lot of your time so if you could at least address the first on I would so appreciate it.
Love what you do here and the service you provide is invalueable.
Sincerely, Tina