I don't know that you necessarily want to change the pack order among the dogs. If the other dogs accept it, then you can create problems by trying to artificially change it.
Your grandson is another matter entirely. When he's going to be with you, make the opportunity for HIM to feed Chloe - under your strict supervision, including, if necessary, holding Chloe back from her food until he has the chance to put it out for her. Have him run her through some obedience exercises (sit, lie down, come). I didn't see anywhere that you mentioned his age, but even a very, very young child can do this with adult supervision.
Of course, it's always a good lesson for children to respect an animal - especially when it's eating. Just make sure your grandson understands the difference.