@PascalDragon - Thank you, but as stated in the beginning of the question there is already an application I want to upgrade, so I know all the basics. I am looking for a high level point of view on the subject, as to how to manage the different memos and threads, for example how a certain thread knows to which memo to write (or maybe it doesn't know and the main application is doing the routing?), that sort of things.
@avra - Funny, I found your application somewhere else on the forum and was already looking at the code! However, in my case there may be several threads, each writing to it's own memo.