You cannot merge os files with each other, so if you have multiple people working with one adapter, they will constantly need to check in and out their files from source control. They could potentially work on separate automations that use the same adapter and you can import those into a master copy of the project, but that is tricky and not advised.

I would not recommend having more than one developer per adapter (at least working at the same time). Creating the adapter is the most important part of a project and requires the most knowledge about how the application works. It also requires knowledge about how it has been setup to match and in what order the matching is expected to occur. Trying to transfer that knowledge is likely a longer process then simply having one developer be the expert on that adapter (at least while they are in active development).