What are the boundaries of what counts as part ot Forgotten Realms?
That depends entirely on your perspective.
You could even make a point that whatever Ed Greenwood thought up, anything outside that isn't 'Forgotten Realms'. OR Everything which TSR/WotC put a FR logo/label on is 'Forgotten Realms'.
Personally I think 'Forgotten Realms' is separate from the planet Toril, or the continent Faerun. And it's far less important what 'Forgotten Realms' exactly is, and more important how different parts interconnect an cooperate with each other. For me FR, AQ, KT, Maztica, Realm Space, Planescape, etc. is all part of the same continuity. If the characters go east enough, they end up in KT, if they go west enough they end up in Maztica, if they go south enough they wind up in AQ, and if they fly high enough, they wind up in Realm Space... When they go underground they wind up in the Underdark, if they go to other planes, they wind up in PS.
But the reality is that in most campaigns we're not doing 'around the world in 80 days' FR style... If players from Neverwinter go to AQ, it becomes an AQ campaign, and vice versa, etc.
Why bother trying to come up with a definition of FR with a couple of folks on the Internet, when the rest of the community wouldn't necessarily agree on what you 'decide' here... Especially when it's a tradition that anything a DM or group doesn't like, doesn't end up in their campaigns. They don't like PS, Spelljammer, KT, AQ, etc. Never going to show up. And that's perfectly fine!
