Block opening Word document in Compatibility Mode

[HonigKlug]

Is there a way to stop a user from opening a document if it's going to convert it to Compatibility Mode? We have a large team working on proposal documents with external collaborators and every time they edit the document it changes to Compatibility Mode. The external users are using all different versions of Word but we cannot control that. Can we just stop them from being able to open the file in Word if it's going to convert it? 

[#2]

There is a policy in Microsoft Office Group Policy to manage compatibility, you may navigate to 

User Configuration\Policies\Administrative Templates\Microsoft Word 2016\Word Options\Save

Take a look at Manage compatibility mode for Office - Deploy Office | Microsoft Docs