I agree with #CherryBomb it can be a long drawn out process until their is a level of trust regarding why you are requiring to attend the appointments. I also do not think it's necessary to be involved in all appointments, just involved regularly enough to be in the loop and and not to long between appointments so that you could miss key information.
To be honest this can all be very dependant on the illness your wife is experiencing. My Mum can feel paranoid at times, so I need to be aware that when I am talking with her about appointments, seeing Dr's etc, just having these conversations can escalate her symptoms. Timing is everything.
When Mum moved in with us she needed to find a closer GP in case of emergency, so we negotiated that we go to one close by however if she ever wants to see her usual GP she does that and I am not involved in those appointments anymore.
In saying all this, I have been involved in Mum's medical management for over 18 months now and she is as well as I have ever seen her and I think even though she was reluctant for me to come along to appointments, I think she now feels more supported and happier.
Tilda 