Toy aggression. Not Jealousy.

Coco sounds like she is (or is trying) to be the alpha dog in the household. However, I would not let her get away with this. As I don't with Molly and her sharing with Mickey.

Since Molly is alpha, I sternly tell her "NO." if she growls at Mickey and take the toy away from her, if she took it from. Since Mickey is not the alpha, I let him growl at her, I actually encourage him to be more assertive with her.