Hi
This is not possible, to see who added which fields. You can not change same file/contnet at a same time, it will be locked by the user.
Even SAP also does not maintain such log for sdk user, to see who added which fields.
And I dont see this is as problem or feasible requirement for SDK tool to maintain such log. I think you should manage debelopment among team.
As work arround you can save your local file( Solution folder YXXXX_) in seprate location after each development by individual developer, and in case of conflict you can check local files saved in seprate location.
Regards
Sunil