Good writeup, seems mostly accurate, although would you mind linking your sources if you still have them around?
One part I'm curious about is SEGA's current relationship with Atlus. The current hierarchy should look like this:
source
Implying that Atlus is under SEGA Games, however you state, and I've seen a source for this as well, that SEGA only lists Atlus as an affiliate, which could imply that they're not fully owned by SEGA. So I'm wondering just how much control SEGA actually have over Atlus. Their financial reports at least act as if Atlus is fully a part of the company.
They are not part of SEGA Games. SEGA Games was made for SEGA games, such as the Sonic the Hedgehog series, Phantasy Star Online 2, Chain Chronicle, and others. ATLUS is affiliated with SEGA Corporation, the entertainment group. At the start of FY2016, SEGA (the game company) became SEGA Games, to differentiate themselves. As you see from the hierarchy, ATLUS is affiliated with the SEGA Corporation consumer division, as they act as the distributor for ATLUS consumer games in Japan amongst other related things. SEGA Games is just the game development and production studio for games developed and published by SEGA in Japan, such as Phantasy Star Online 2 (by SEGA) or Stella Glow (published by SEGA) SEGA Games uses the regular SEGA logo for their games, and a similar logo on the SEGA Games site.
Here's the source:
http://sega.co.jp/corporate/profile_group_j/
ATLUS is listed under "関連会社" which means "associated group(s)" or "associated company." Meaning, they are not part of the "グループ企業" (group businesses) category, which would mean they are part of the SEGA group and not just affiliated with SEGA Corporation. The reason you see their financial reports act as if SEGA acts for them at times, is because their financial holdings and stokebroker, including stock number, is associated with SEGA SAMMY HOLDINGS. However, nothing ATLUS related is done by SEGA except for distribution. SEGA has very little control over ATLUS as a company, from what I've gathered.
And this is SEGA Games, for reference:
http://sega-games.co.jp/
The site for SEGA SAMMY HOLDINGS lists ATLUS and every other associated company as part of the Group, even though that is not the case. The list on the SEGA Holdings site seems to be more accurate, as it has different sub-categories.
I hope this gave you the answer you were looking for, Crimson. I'm always here to help when needed.