Thanks for your reply. "Data entry" of the form is already set to "No". Is there a similar setting for subforms?
Gasman's answer is correct. I'll clarify a little. The ONLY difference between a form and a subform is that a subform is a form contained in a subform control, just like a picture is contained in an image control, or a subreport is contained in a subreport control. (Actually, subforms and subreports are in a subform/subreport control because that control goes either way.) Subforms actually don't exist UNTIL you build a form that then can be put into a subform control - and then put it there. Therefore, whatever properties you wish to adjust on a subform, the trick is merely addressing it correctly. Otherwise there IS no difference between forms and subforms.
The subform control provides linkage to synchronize the subform to the parent form. However, a subform is EXACTLY like a form in that you see whatever the .Recordsource and other controls make available. Just remember that forms and subforms have separate .Recordsources and other controls, so they behave independently (except for that parent/child linkage managed by the subform control.) If something appears or disappears from a given form or subform, the first place to look is locally to the offending form or subform. The next place to look would depend on whether there exists a formal declared relationship between the record sources for the two forms such that some records get excluded.