>Hi!
>
>>Grid is just sub-classed from base classes
>
>Maybe it comes from the base classes? What if your base classes at some moment do something that adds a column? Or just they contain a one column already? I did met a lot of problems when grid has a column in the base classes. Check if ColumnCount property contains default value in all classes for grids and their parents.

The grids are sub-classed from the VFP _Base.vcx and the default ColumnCount = -1 in _Base.vcx. I don't have any code in my sub-classed grids that add a column. I've even hard-coded the column count in my grids. It's very strange, I've never used the data environment with persistent relationships before.