
Hi Christine,
I think this may be a case where your dachsie is forgetting her place! It sounds as if you need to lower her rank - and she won't like it at first! (And you probably won't like doing it.) If she growls at people when she is sitting with you on the sofa, you are going to have to keep her on the floor, ideally all the time, but if you don't feel you can bring yourself to do that, don't let her choose when she can get up -
you decide that, and she only comes up when she is invited. And she gets off when you decide, too.
Your uncle is right - as soon as she starts to growl, have nothing to do with her. Put her on the floor and walk away, basically ignoring her.
She really has to know that she is bottom of the heap.