Managing your managers

Hi 

I was just wondering what is the best way to manage a manager who is not officially your manager. 

I guess I am confused because I have an assigned manager. My assigned manager doesn't have the same kind of technical expertise that I bring to the team, but oversees my projects.

Someone else on my team who does have technical expertise is hosting weekly O3's with me, and sometimes seems to overexert influence, especially when we are in actual meetings with the person who is actually my manager. In those situations, I feel sometimes overshadowed, in others, it seems I'm micro-managed.

I think it's a manner of style but I'm not sure how to broach the subject with this other person who has a lot of influence and is also helpful in guiding me in my projects. 

Also should I try to do "updates" with my manager? 

Thanks for your thoughts.