Is there a way to associate an Add In with a xlsx spreadsheet so that the Add In is available when the spreadsheet is open, but not for other spreadsheets without the user having to manually include or exclude the Add In,

I have an Add In with a custom ribbon and do not want the custom ribbon displayed for non target spreadsheets. The target spreadsheets are xlsx spreadsheets and providing extra functionality via an Add In allows a single point for maintenance of the code as well as avoiding the need to individually convert each spreadsheet. I should also like to avoid having to convert the spreadsheets to xlsm and use code to set and unset the Add In as users invariably save them back to xlsx.