Combobox Requery from a different form.

Hi,
Using MS-ACCESS.

I have this:

A Form called:  FormSalesHead

Inside this Form I have a TAB.  Called:  Tab1

Inside the Tab1 I have a Subform Called: FormSalesDetail

Inside the FormSalesDetail I have a combobox called: SProductID.

Sometimes I am recording a Sale on this forms and I need to ADD a NEW item, which is not on the List of SProductID (Combobox).
Then I go to another form called Products, and there I record the new Item.

Then I come back to the Sale, but when I look in my Combobox (SProductID) the New Item is now in the list still.

I know I could solve this doing a Requery action on get the focus on this combobox, but the issue is that there are thousand of items and it will make the process slow every time this combo get the focus.

How can I requery this Combobox from the Products form (the form I use to add the Products?

I have tried this from the other form (Products):  Forms!FormSalesHead!FormSalesDetail.Form!SProductID.Requery   but not requering / working.

I also tried this: orms!FormSalesHead!FormSalesDetail.Form.Requery      > This requery the form... but not the Combobox.

Please advice.

Thank you.