Are there any co-authoring options for reviewing documents in Hubshare?

Hi, 

I have seen the option for creating annotations which are saved as different files, but that is not what our users want.  The only option is file versioning, but that requires users to check-out/in and access the document one at a time.

Could I set a document as checked out for co-authoring in M-Files and put a link in Hubshare? 

The reason that I am going for the Hubshare option is because, I want external customers to work in a central place with all other related documents.

Thanks in advance,

Irene