Optional Dependency in VBA Module

Background I am developing a VBA module (call it "Greg") for VBA developers of Excel UDFs. The purpose of Greg is to enhance the experience for the end user, who uses those UDFs in Excel. The developer must simply copy a snippet into their own module (call it "Dev"). If Greg is loaded, the snippet enhances Dev's behavior. Otherwise, it has no impact on behavior, but it does prompt the Excel user to import Greg.bas. Approach Here is a simplified sketch of Greg.bas... Attribute VB_Name = "Greg" ' Keep these functions invisible to Excel users. Option Private Module ' Enhancement function. Public Function Enhancer(Optional x) ' ... End Function ' Assert the 'Greg' module is loaded. Public Function IsLoaded() As Boolean IsLoaded = True End Function ...and of Dev.bas: Attribute VB_Name = "Dev" ' Some UDF by the dev. Public Function DevRegular() ' ... End Function ' ############# ' ## Snippet ## ' ############# ' Use the enhancer, if available via the 'Greg' module. Public Function DevEnhanced(Optional x) If Enhance_IsSupported() Then DevEnhanced = Greg.Enhancer(x) Else DevEnhanced = DevRegular() ' Prompt the user to import the enhancer. MsgBox "Import the 'Greg' module to enhance your experience." End If End Function ' Check if enhancement is supported via the 'Greg' module. Private Function Enhance_IsSupported() As Boolean On Error GoTo Fail Enhance_IsSupported = Greg.IsLoaded() Exit Function Fail: Enhance_IsSupported = False End Function Problem While this has worked sporadically on Windows, it has often failed there and always on Mac. The crux seems to be Enhance_IsSupported() within Dev: Private Function Enhance_IsSupported() As Boolean On Error GoTo Fail Enhance_IsSupported = Greg.IsLoaded() Exit Function Fail: Enhance_IsSupported = False End Function I assumed that the line Greg.IsLoaded() would compile, even if there were no Greg module present...and it does! It only fails when a Greg module exists without a member called IsLoaded(). Unfortunately, it seems that VBA does not reliably refresh its "awareness" of a Greg module with an IsLoaded() function. When I import Greg.bas and Dev.bas together, everything works as intended: Enhance_IsSupported() returns True, and it updates to False if Greg is removed. But when I first import Dev.bas and run DevEnhanced(), and only afterwards import Greg.bas, then Enhance_IsSupported() apparently returns False despite the presence of Greg. Note This latter workflow is absolutely essential: an Excel user must first run DevEnhanced() and see the prompt, in order to know about Greg.bas in the first place! Failed Solutions Unfortunately, no experimentation has availed. In Greg itself, I have tried using a constant... Public Const IS_LOADED As Boolean = True ...and also a procedure: Public Function IsLoaded() As Boolean IsLoaded = True End Function In the snippet for Dev, I have implicitly tried Application.Evaluate()... Private Function Enhance_IsSupported() As Boolean On Error GoTo Fail Enhance_IsSupported = [Greg.IsLoaded()] ' ^^^^^^^^^^^^^^^^^ ' Application.Evaluate("Greg.IsLoaded()") Exit Function Fail: Enhance_IsSupported = False End Function ...but while this works for Enhance_IsSupported() itself, the same error simply crops up elsewhere — like whack-a-mole at other instances of Greg.* — and only a manual edit will "refresh" those procedures. I would also prefer to avoid unstable calls to any .Evaluate() method, even in the Worksheet scope. Questions * What is the simplest way to "refresh" the Dev module, such that its procedures now recognize the calls to Greg.*? * Is this possible without resetting cached or Static variables in Dev? * Can this be done with an IS_LOADED constant rather than an IsLoaded() procedure? Bonus * Can this refreshment be done by some Sub like Dev.Refresh(), called automatically at the start of Enhance_IsSupported()? * Can this refreshment be done by some Sub like Greg.Refresh(), as run manually by the user in the VBA editor? --- This project represents a great investment of my time and energy, and it is otherwise operational, so your help is greatly appreciated in conquering this final obstacle!