I hadn't seen a comprehensive timeline of the Eagan family/Lumon CEOs, yet-- so I made one. It's imperfect, for sure, but I hope you will let it help you.
The blue text indicates the birth year of the family member, while red indicates the year of their expiration.
The Green represents the transition of power between CEOs.
(Edit: There is conflicting information about the transition of power from Leonora to Jame. I have since seen on Lumon's website that Leonora ended her time as CEO in 2008, NOT 2003. But the Severance Wiki page states that she died in 2005. So... how is this possible? What is the truth? Any theories?)
Things I noted while making this:
Jame Eagan has no known birthday, therefore we have almost no idea where/how he fits in the family. This omission seems intentional on the writer's part. I have a lot of theories about Jame Eagan, and how his leadership has changed the direction of the entire company, but I'm saving them for a later post.
I feel that there is also more to the story when it comes to Myrtle Eagan. Perhaps a power-struggle of sorts. We know that Ambrose is "often maligned" (and don't they say history is written by the 'victors'?). We know that Myrtle was determined to be CEO from the age of 7, which is shown in an aspirational light in the Perpetuity Wing, but what if her ambitions are less virtuous? The two of them are so close in age, I can't help but feel Myrtle would have grown up aspiring to be in Ambrose's position. He only served as CEO for two years before she replaced him. Just something else about this family I've been pondering, in perpetuity...