Hi Dave - thanks for replying.
If no booking exists then the form will open in Add mode:
If btnBkg.Caption = "Amend Bkg" Then
stLinkCriteria = " [BkgContactID] = " & Me.[Contact ID]
DoCmd.OpenForm stDocName, , , stLinkCriteria
Else
DoCmd.OpenForm stDocName, , , , acFormAdd...