Thanks so much for answering my questions. Yes I mostly fly domestic flights now, and if I do international, OZ is not my first choice anymore. That's why I want to switch the program to take advantages of the hidden benefits of UA silver or gold.

I'm interested in your suggestions about changing the membership number after entering the lounge, since that would be a good way to enjoy the*G while i try to earn more miles on MP. But It sounds kinda tricky. is it normally allowed to do so? Would the staff refuse to do so upon any reason?