Sorry, posted too early. The second link is a similar conversation where you may find some advice. For some reason it was in "Arts and Crafts" so it took a while to find.
I think once you’re used to GN most posts are easy to read and understand. Recently a thread was started about neighbours (written in full) but further down a poster used NDN - next door neighbour, which became clear because of the content. I agree SinL can be misleading, but if a poster has referred to a brother and his wife, then the SinL in question is obvious? I don’t mind the abbreviations at all and if I’m really interested in a particular thread, I’ll read it.
IHT as the title of the thread recently, which stood for Inheritance Tax. I have googled these abbreviations and they usually refer to names of businesses, so no help at all. It doesn't take long to write two or three words at least once in a post.
I don't use many on the list but I do use IMHO, In My Humble Opinion, a common internet abbreviation, when I want to be clear that I'm not stating A Truth, just what I think.
I've also used OVMV, Others' Views May Vary, which I thought was what the Queen said about Prince Harry's book. I've just googled it, and it's not what she said and it doesn't exist as an acronym, so I'll withdraw it!