I actually feel like it makes more sense for Max to be the son of Maddox rather than the son of the Mad hatter. I only found out today but the actor who plays Maddox (Leonardo Nam) is 45 years old and is turning 46 at the end of this year while the actor who is playing Max (Brendon Tremblay) is 21 years old.
Oh also Max's real name is Maxwell Tarrant Hightopp Hatter (My opinion). I don't like how all the names are basically shortened names of parents so Maxwell. Tarrant and Hightopp both come from the fact that in a version of the mad hatter his real name is Tarrant Hightopp so Maddox is honouring his father and the Hatter part is from the Mad hatter keeping his last name while also embracing his title.