>> i want to manipulate the data in a grid column by a combo
box.
What do i have to take into account? <<

Personally, I think that setting Sparse = .F. for the column that contains the combo box looks cluttered and busy. What I generally do is create either a local view or an updateable cursor that contains both the foreign key value from the lookup table (presumably the value you want to bind to) as well as it's description to use as the RowSource for the grid. I then bind the column that contains the combo to the description and put some code in the combo's Valid to update the foreign key field in the grid's recordSource.

This technique works quite well for me.

Marcia