Spec Sheets - Contractor Collaboration

I think spec sheets could be useful to use with contractors. I'd like to be able to create a spec sheet (or something similar) for a contractor that lists various works we have discussed and agreed to (a confirmation of works) and have them be able to collaborate - naturally without them having to subscribe to a full version of DF, just a portal that allows them to comment and upload imagery & links to the spec sheet. This would keep all project milestones, communication, feedback etc in one place. It should be shareable with the client and exportable