Diamond Invitation are also those who are ahem invited to diamond. Usually people identified as influential within heir field/company that can sway dollars towards CX.
I'm not totally sure? I know folks who have been granted DM for this purpose, but they don't get IN. It's just regular.
I know and have traveled with folks who have "VIP" on their boarding pass. But that's clearly something else. IMO Diamond IN don't get anything special on-board in the limited instances I've seen it. VIP is a totally different league.
The only IN I know was a "lifetime Diamond" or something like that. What the fellow above is referring to. He earned it before they took that away. My impression, maybe it's wrong is just that IN are treated the same as normal DM.
Whereas DMP is a cut above, as is obviously VIP.