Allow groups of users to edit a single Webform I need to enable groups of users to edit one Webform so that they can collaboratively complete a questionnaire. I am not concerned with two people editing at the same really.

I've seen mentioned the Organic Groups module and the OG Webform module to enable this but as far as I can tell it isn't suited to what I want to achieve.

The other option seems to be to implement hooks in the Webform module to override the user authentication but I'm afraid I wouldn't know where to start with that. How would you define the groups of users and then allow access to the forms based on those groups?

Any help would be massively appreciated!
If you can group those users in a role, you can use the Content access module to allow them to edit the webform. 

Furthermore you can set content access settings per node, so you can limit them to be able to edit only that one webform.