Branch Transfers & Bonsai Grafting
I think I may have figured out the significance of the bonsai tree in Milchick's office, and the wound cream for healing cuts in the tree.
I previously theorized that Miss Huang is essentially the new Ms. Cobel, having somehow taken on Harmony's traits. See:
https://www.reddit.com/r/SeveranceAppleTVPlus/s/77VNn1x6VQ
Now I see that the bonsai tree, which symbolizes HARMONY, is the plant that took fertile root in Lumon soil, and whose branch was cut to be grafted onto Miss Huang.
"We must be cut to heal."
Harmony has a needlepoint sampler in her basement that outlines the nine core principles. The last line is, "I was Me till you gave me You."
The logo for the Myrtle Eagan School for Girls is Myrtle's initials:
ME
Myrtle was a biological child of Kier. What if elements of her personality have been grafted onto other people in a long line. Charlotte Cobel received this branch transfer, and Harmony received this graft from Charlotte, and now Miss Huang has received it from Harmony. This explains Harmony's presence remaining in Milchick's office, and the welcome message, which is actually for Miss Huang, who now has a part of Harmony transferred to her.
This could also explain the weird similarities between Mark S.'s original MDR team and the new team.
It's been observed that Dario physically resembles both Irv's father and Irv himself, who resembles Ambrose Eagan, another biological child of Kier. See:
https://www.reddit.com/r/SeveranceAppleTVPlus/s/5DMxuzw4Kj
At the same time, Dario and Dylan have parallels. They both observe that Mark is standing weird, or strangely. They both mention someone being poor. The writers draw attention to this by having Dylan ask Mark, "Who was me?"
Dario and Mark S. also have the parallel of the head cube, and Mark S. has the same name as Mark W., both of whom question the fact that Miss Huang is a child.
At the same time, Mark W. is like the Irving of the new group in terms of age, style of dress, and his propensity for correcting people, as he corrects Gwendolyn regarding puce vs. purple.
Bonsai trees can also represent immortality, as they are very long-lived. So what if Kier has achieved a kind of immortality by repeatedly grafting parts of himself onto other people, via his biological children first, and then through indoctrination (school, lore, writings) and some sort of surgical or technological procedure that grafts parts of his "children" onto new subjects.