Last grid position when button clicked

I have a typical app with a grid in which one column contains a key
field in another table.

On a single record form I could have this field  entered via a dbcombo.

In the grid I have used a function key to trigger a lookup on the
current field for the current record and that works OK. If I want to use
a lookup button can I

1. determine which grid cell was active before the button was clicked.
2. perform the lookup and return the value to the cell without the grid
forcing an update.

Alternatively is their a way to insert combo or dbcombos into grid cells

Kym Wilson