This is going to be official as it gets.

CC2 Pro
Campaign Mapper
FRIA
DD2
CD2
Dioramas
CA
SS1
SS2
WW2 IA
Perspectives
SS3
Cosmographer
Source Maps Castles
Tome of Ultimate Mapping
Universal Update 8
Source Map Temples
CHMP (Harn toolkit)
Fractal Terrains

Campaign Mapper & the Forgotten Realms Atlas need to be installed after CC2 & don't forget that CM has a patch that is essential, otherwise you get the wrong symbols. The FRIA has 3 updates. There it's a bit fuzzy - the last one is supposed to include everything but I think it misses a few things. If you install all 3 updates, in order, make sure you clear the read only flag on the Maps folder before each installation, otherwise some maps won't get updated.

Really the rest of the add-ons don't matter, except Source Maps Temples - it has to go in after UU8. CHMP can be added at any point - it backs up & modifies the menus, so your best bet it to do it at the end.

FT is independent of CC2, so install it first or last - doesn't matter.

I've lost my copy of Overseer somewhere along the way, so I don;t know what it does or doesn't do to the menus. It should have a readme file that explains how to add the items to the menu if they get missed. I'd suggest installing everything else & then manually adding in the Overseer menu items to make sure they don;t conflict with later updates.