>>I looked into this KB article, but it seems to be related
>>to insertion (INSERT COMMAND) and I'm not doing any insertions
>>AFAIK in this application.
>
>I was afraid that this would not bring us any further

Ok, I was able to make a completely reproducable scenario.
I open file in Parcel Standardization, change Street field in the record, don't move yet from this field.

On another machine I'm invoking Owner Standardization for the same file, find the same record and try to change another field OwnerStrt. I got an error "Record is in use" and the alias is uncorrectly reported to be Login, while in reality it's a BldMstr table.

I didn't get the same error in BldMstr Editor. I took out all code from AddrInGrid class (InteractiveChange, GotFocus, LostFocus) and I'm still getting the error.

So, now I'm going to take out code from Grid.AfterRowColChange method and see, if the error will get away. If yes, the problem is narrowed and could be solved, if no, I will have to continue to beat it...