Managing SQL Server logins and database users
The easiest and most manageable way to achieve this is using Active Directory groups.

Have your ad administrator create a security group called SQL_Writers (or something similar) for those users and add them (and any new users to that group).

Then in SQL Server, simply grant that security group the appropriate permissions to the server / databases.

If you want the permissions to be inherited to any newly created database on your instance, remember to grant the security role to the model database as well.