Form opens for new record but want to edit existing records

I have a form that opens for a new record via an onclick event of another form:

DoCmd.OpenForm "frmInventoryTransactions", acNormal, , , acFormAdd, acWindowNormal

But also on the is a "search" combobox.  When the user select a record from the combobox is there a way to make the form become record editable?

Or do I need two command buttons on the first form... one for new record and one for a searchable and record editable form open?

--Steve