[Merging QBWs] One workstation using a different company file than everyone else

Experts,

I have a workstation that cannot connect to a company file that all others have no problem with. Tried everything (yes, 3 re-installs), no joy.

Finally called support yesterday afternoon, who are always great, even though nobody ever finds out what the root cause of an issue is. We just keep trying things until the symptoms go away. Imagine if everything in life was like QB...

So as part of the error codes -6190, -816 and the -6000, -83 codes we get on that W/S (one of these common pop-ups attached, but attachments on the fritz today), is to have the odd W/S open a backup. It did.

We open up the 'original' company file, and it all seemed well.

[this morning] They call and say that neither side ('good' W/S vs 'bad' one above) can see the others' changes. Oh, great, the 'bad' one isn't on the right company file...

Yes. Sure enough it is somehow on the backup.

Well, you can see the issue. Not only can I still not connect that W/S to the 'correct' company file without the -6000 & -6190 errors, but now I have a QBW file that is 'out of sync' with the 'good' one, and I'll eventually need to somehow get those activities on the 'good' QBW.

My question, as you see, isn't about the common -6190/-6000 problem without cause, but about how to get those 'rogue' activities into the 'main' QBW if/when I get that W/S connected to correct QBW in multi-user.

So basically, how to sync/export/import activities on one QBW file into another?

TIA!