>The two grids have different names and the recordsource (grid) and controlsoúrce (columns) are
>definitely not changed.

That is the problem. If you are reselecting into its record source then it would lose the source in between and the grid would be rebuild with defaults. Prevention is very simple:

local lcRecordSource
lcRecordSource = thisform.myGrid.RecordSource && save the source
thisform.myGrid.RecordSource = '' && temporarily set to empty string

* do your reselect into cursor here
* and reassign the source

thisform.myGrid.RecordSource = m.lcRecordSource