Black phone theories

Theory 9- max

So in the movie  we all saw the grabbers brother max .
Max didn't get much screen time so I don't know much  so these may not be the best .
In the movie max seems very interested in the case of how the kids went missing some people think that max knew about the case. I don't really know if he was involved because  and it didn't seem like he knew what was going on. But it's possible. (Ill talk more about that towards the end)
Also it's possible that max and the grabber aren't even siblings  because they don't look alike (I know all siblings don't look the same) But I've heard something interesting about them and I think also the grabber might have done something to max (not sure what ) I think max knew about the kidnapping the whole time and wouldn't say anything and played off because he knew what the grabber would do and maybe that why he was acting so weird when he found finney.
  Maybe I'll do another theory on max .
That's all for this theory since I don't know much on max but tell me what you think?  (Sorry it's so short and that I haven't been posting)