Please Help!! My hunting dog is regressing!!?

In my experience dogs are very much like human children. Any attention, even negative attention is attention. She is "demanding" more attention, just as the younger dog "demands" attention. She is smart enough to see that the younger dog received more attention by acting up (normal puppy antics) and she is giving it a go to see if it works for her too. Maybe it would help if your husband would give the 3 yr. old dog one on one attention, such as play time, walks, car rides it would help.