Have you tried setting the focus on the first field in the Subform header? try setting it in Subform "Onload" event.

I asked Chatgpt this before.  Haven't tried it but here is what it said.

o achieve the desired tabbing sequence in your Microsoft Access form'where the focus moves from the parent form to the subform header and then to the subform detail'you can follow these steps:

Step 1: Set Tab Stop Property for the Subform Header Controls
Open your form in Design View.
In the subform, make sure that the controls in the header section have their Tab Stop property set to Yes (this allows them to be part of the tab order).
Adjust the Tab Index of these controls to ensure the proper tabbing order within the subform header.
Step 2: Adjust the Tab Order
Right-click on the parent form and choose Tab Order from the context menu.
In the Tab Order dialog, ensure that the subform itself has the appropriate tab position relative to other controls on the parent form.
Right-click on the subform and choose Tab Order to set the tabbing sequence within the subform.
In the subform's Tab Order, make sure the controls in the header section come first, followed by the detail section.
Step 3: Ensure Focus Shifts from Parent to Subform Header
By default, the focus goes to the first control in the subform detail section, but you can adjust this behavior by setting the focus to the first control in the subform header programmatically.

In the parent form's On Exit event for the last control that should move focus to the subform, add VBA code to set focus to the first control in the subform header:

Private Sub LastControlInParent_Exit(Cancel As Integer)
    Me!SubformControlName.Form!HeaderControlName.SetFocus
End Sub

Replace SubformControlName with the name of your subform control, and HeaderControlName with the name of the control in the header where the focus should go first.  Sorry for the long post but consider the source that tried to help me.

This will direct the focus to the subform header when tabbing from the parent form.

When you tab from the main form to the subform, it lands on the control that you were at the last time you were at the subform.  So, to tab from the main form directly to the subform's header, you need to be in the subform's header the last time you were at the subform.  You can use VBA code to set focus to wherever you want, of course.

You cannot tab from header to detail to footer, because each section's tab order is independent of the other sections' tab orders.  You need to click the sections manually or use VBA code to set focus to wherever you want.

You can use the F6 and Shift-F6 keys to jump between the different sections of a form.

You can also do this with 2 lines of VBA code when you enter the subform - put the focus where you want. Like:

Details

Private Sub OrderDetailF_Enter()

    DoCmd.GoToRecord , , acFirst
    OrderDetailF.Form!ProductName.SetFocus
    
End Sub
Copy

I've actually had this on my TechHelp list for a while now. I'll put a video together for it. Stay tuned.

You can start with this: Subform Goto First Field

Thank you so much. It worked!

And yes, you did pronounce Lytle correctly.