This is easy to do, let me remember...
1.- Put a Grid on a Form
2.- Set the grid controlsource and the columns rowsource
3.- Right click on grid and from Context menu select Edit
4.- Select the desired column to put the Combobox (on the white area of the column, not the header)
5.- From the Controls Bar select the combobox control
6.- Click on the column (on the white area of the column, not the header)
7.- Set the properties to the Combobox
8.- From the Properties window select the column and in Data select CurrentControl property and change for Combobox1 from the list
9.- End

I hope this help

Mauricio Flores Olmos