How will this query object fix locations that used an SQL statement in RowSource? Or did they all reference a query object? If you want to use query object then must use full form/control path per Ranman example. If you are trying to fix multiple comboboxes on multiple forms, this referencing will not work unless they are all dependent on the same Forms!formname!cboVendor.
Assuming comboboxes are on same form, dependent combobox can have RowSource as SQL statement like:
SELECT qryVendorToPart.PartID, qryVendorToPart.PartNumber, qryVendorToPart.PartName, qryVendorToPart.VendorID
FROM qryVendorToPart
WHERE (((qryVendorToPart.VendorID)=[cboVendor]));
Then VBA just needs to Requery combobox:
Me.cboParts.Requery
Otherwise, yes, VBA will set RowSource = "Some SQL statement"
Still, there is no need for recordset object.
Be aware that dependent combobox using alias will not work nicely with form in Datasheet or Continuous view.