I've followed and read the thread.... My .02...
First... caring for someone is a HUGE stress. My mom had Alzheimer's, my dad cared for her alone until she almost killed him. He wanted to do well by her, he cherished her, they were married over 60 years - but it simply became too much. Caring for someone is tough emotionally and physically but mentally it's just a nuclear bomb going off that sneaks up and can destroy you. You have given up of yourself, your life, your freedom. It is NORMAL to feel stress in your situation, it is NORMAL to feel frustration, it is even NORMAL to feel resentment! It is okay to feel all that, but you do need some 'out' to let things GO someway, somehow, weekly, regularly or this is going to destroy you.
Second... it is NOT just Amanda causing issues with those puppers you dearly love. Your puppers love you and they are sensitive and YOUR actions, feelings, are so pent up, I can feel them in reading your posts - how can you expect your puppers to not feel them when they are with you day after day? You AND Amanda are causing your puppers issues.
You have been given great advice here. You said you have a camper available? GREAT! A bit of separation and an opportunity for some privacy, a place to escape to is a great thing! Amanda? Get a large crate if she does not have one - Amazon has great prices on crates, they used to be SO expensive. Get a nice crate pad for her, make sure she is comfy and cozy even if it kills you to be nice to her. Crate Amanda at least breakfast, lunch, dinner. Put the crate in an area where it can be semi quiet, away from the hustle and bustle of the house. Make sure she is fed, watered, pottied and put her in her crate for at least those 3 times a day. Buy a large Kong, fill it and leave it with her in her crate. She can stay there while meals are prepped, eaten and cleaned up after. Do NOT allow anger to overtake you and use the crate for punishment or leave her in there past the time it takes for those 3 meals - you will be tempted - DON'T. She might howl, play some soft music, cover 3 sides of her crate, not all 4, to give her a safe, den like area without it being dark and dreary and scary. If it was your pupper, how would you like THEM to be treated? It won't kill you to treat Amanda the same. AND, in the process you are not only addressing a food stealing issue which has become commonplace, you are also giving your puppers some freedom, and lowering the stress levels in the house. Remember, YOU are contributing to this as much as Amanda is. Amanda might howl, play some soft music for yourself, soothing, no place for rap or hard rock here - upbeat, soft, expose yourself to some new music if it isn't your thing currently - music tames the savage beast in all of us if we let it!
Amanda can NOT make the change here. You have given up of yourself to take care of someone else, you knew the parties involved beforehand. Stuff has gotten bad, but Amanda can not make positive change - only YOU can. What you are doing was initially a GREAT thing, but the situation you got yourself in has got you all tied up, it is more than you thought it would be and I imagine you feel trapped. The ONLY way you can begin to make changes for yourself, your puppers, Amanda, is for you to step back, take a deep breathe, and change yourself FIRST.