Maybe you can try to incorporate your husband's connection with her by having him specifically back you up when you suggest something to her. I don't know your situation, but something like, "Yes, that's a good idea!' If she listens to him and can possibly understand that HE thinks you are "right", maybe she will accept your help more. And maybe, a bit later, he can talk with her and explain how much he better he will feel if she listens to you.
Something like this...