How to set up "email threads" in Outlook using MS VBA?

Question

Visual Basic

Good afternoon!
There is a task - to make a very simplified analogue of CRM based on Outlook for personal convenience.
Now I have Outlook 2019 on my computer, mail goes through Exchange in the MS Office cloud
I really want to avoid Exchange settings or use some auxiliary MS solutions, I want to get by with only Outllok on my computer and VBA
Task.
Using VBA or a self-made plugin (or maybe someone has already done it, but I can’t find it), learn how to combine disparate letters with completely different topics and from different respondents into “chains” based on the “order number”, which I must assign myself every letter.
Problem.
I can't understand the principle by which Outlook creates these "Chains"
Previously, in order to "deceive" Outlook and force the letters to be combined into a "conversation chain", it was enough to change the subject of the letters to the same one (well, add Re: to the beginning of the subject) and these same chains were formed, now, starting with Office 2016 - don't change , and it is no longer possible to "deceive" the internal mechanism of the formation of "chains" - how the letter got into the chain, don't change it, it will be in it.
And vice versa - add an already received letter to an existing thread by replacing the subject, etc. does not work.
I hope it's just that I have not mastered how to do it =)
Situation:
I place orders with a large manufacturer, in fact, acting as a sales manager on an outsourcer.
The supplier sends me letters from his system about the readiness of the order, dealer and retail cost, some other details - IMPORTANT, all letters have different "Subjects" (Subject), they have stupidly configured internal CRM, moreover, they switch to another and with this they have been in a mess for 3 years already...
On the other hand, I am in active correspondence with many clients, the subjects of letters related to the same order are again completely different and I cannot influence this.
Therefore, solutions like "ask everyone to write the same topic or mention the order number in the letter" unfortunately do not work.
I also ask you not to offer to work through a third-party CRM, it’s not at all possible for me to create all these customer cards, leads, etc. especially since I'm actually creating them in a vendor-supplied wrapper, but it can't handle mail.