Close any open .PDF-file using VBA - vba

Question

I use 'Close_by_Caption' to close open .PDFs before they are regenerated. Previously this was easy because I could assume that always 'Foxit Reader' opened the file and that each file was opened in a separate instance of Foxit.
Newly, 'PDF-XChange Editor' should also be used to open .PDF. Now I don't know if I have to close the file with 'Close_By_Caption 'Demo - PDF-XChange Editor' or 'Demo.pdf - Foxit Reader'.
Of course I can run both commands one after the other - but surely someone will come soon who wants to use another viewer....
Is there a way to find all programs that have the word 'Demo' in 'AppCaption'? Of course, it would be even better if I would knew that either the program is a .PDF-viewer or the opened file is a .PDF...
'API Find application by full caption
Private Declare Function FindWindow _
Lib "user32" _
Alias "FindWindowA" _
( _
ByVal lpClassName As String, _
ByVal lpWindowName As String _
) _
As Long
'*****************************************
'API Bring Window to foreground
Private Declare Function SetForegroundWindow Lib "user32" (ByVal hWnd As Long) As Long
'*****************************************
'API Send message to application
Private Declare Function PostMessage _
Lib "user32" _
Alias "PostMessageA" _
( _
ByVal hWnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any _
) _
As Long
'*****************************************
Const WM_CLOSE = &H10
'*****************************************
Function Close_By_Caption(AppCaption As String)
Dim hWnd As Long
hWnd = FindWindow(vbNullString, AppCaption)
If hWnd Then
'Bring to Front
SetForegroundWindow hWnd
'Close the app nicely
PostMessage hWnd, WM_CLOSE, 0&, 0&
End If
End Function
'*****************************************
Sub Test_Close()
Close_By_Caption "demo.pdf - Foxit Reader"
End Sub
'*****************************************```