当然要交代清楚，否则别的组怎么知道你们内部分工

不过，表达方式正式一些为好，我觉得你发出的信号有点儿模糊，这事儿年初已经商量过了，就得按既定方针办，大家都根据process来做，该怎么着就怎么着，明确责任，保证质量。

dear group B memebers,

this email is to clery the job responsibilities of project ABC & XYZ. early this year, it's been decided that john is accountable for project XYZ, and I ABC. As a team johny and I support each other internally when necessary, it's critical to follow up the process when you have new requirements, lest project being delayed by miscommunication. In order to make sure you are serviced promptly and properly, all ABC related works should be sent directly to me, and XYZ to johny. Should you have any questions or concerns, please feel free to contact my group manager donny, or me when he's in absence...