Here's a piece from the Chicago Tribune that may give you an indication of an approach:
"Rather than emotional pleas, parents are asked to use empathic but firm declarative statements, such as "I'm no longer going to let you starve," "This is your medicine" and "I won't give up," said Katharine Loeb, an associate professor in the school of psychology at Fairleigh Dickinson University. She is also director of the eating and weight disorders program at the Mount Sinai School of Medicine.
During this challenging first phase, normal life stops until the sufferer eats. Parents may quit jobs, take leaves, cancel all social engagements. It's lonely and exhausting for everyone.
"It's a matter of wills," said Ranalli, who ate lunch with her daughter at school to make sure the girl wasn't throwing the food away. "As a parent you are stating, 'I'm not leaving, I'm not caving, I'm not negotiating. We are not leaving this table until you eat.'"
It would be helpful to emphasise the right here right now aspect of what is happening, and avoid any reference to what might happen in the future "IF..." My 9 yo DD will not do her homework because of me telling her she will never become a CPA if she doesn't finish her sentences and get started on her science, nor will she do it because I tell her she will become a bag lady if she doesn't do her homework.
You know the big picture, and the eventual consequences, but the anorexic is willing to take her chances. The big picture sounds like rhubarb rhubarb to her. And it won't happen to her anyway. An anorexic doesn't believe she is mortal or she wouldn't be anorexic in the first place.
It's important to separate in your minds, and in hers, the anorexia from the child. So associating the anorexia with something that is going to happen to her personally and physically is getting the two mixed up. She needs to understand that she feels the way she does about food because something in her brain is not working right and giving her thoughts about food that she needs to recognise as her enemy; she needs to learn to use another part of her brain to counter those thoughts. Initially she can use her hands, knife, fork and spoon to counter those thoughts. A ten year old is capable of weeing it in those terms.
Try to use the declarative statements and focus completely on the eating of this one meal that is before you on the table without referring to the IFs.
Initially you may be all sitting there til the cows come home. You can expect a huge amount of resistance, but you must persist. You may need some sort of reward system or some sort of timer system where she must eat for a certain period of time and/or eats what is served -- maybe initially anything high in calories no matter how unsuitable it may be for dinner (milkshake with protein powder, anything you can think of that would help her gain weight). It doesn't have to be a healthy snack. It just has to have a lot of calories. Time enough to discriminate among foods when she has gained weight and is learning to eat voluntarily.
You are going to be laying down the law here in no uncertain terms, while trying to keep your cool, focusing on the here and now, and not allowing the ferocity of the resistance to make you retreat.