I think that Max was always Charlie's target, not Dot. The most recent episodes seem to hint strongly at this. He's probably pulling a long con on Max since he's obviously the one in the family with a decent amount of money.

I think Nick employed his son to do fake his death for a reason of which we are yet to learn, because he knew his son wouldn't blab, but I think upon seeing Dot, Charlie fell in love with his Grandma and couldn't bring himself to disappear from her life. So Charlie became close to Dot and carried on seeing her behind his back , which Nick doesn't like, because it'll ruin his plans.

Agree. That sounds most likely.

I did think what if they have to move Jim and thats how the secrets all come out?