How to share one plan only

Hi,

I have created a group for all my projects and this is private. Each projects has  a plan created within the group. I am the only member. However, I would like to find a way to share only some of the plans when i go on holiday so my manager can view the progress of those projects. But today I tried to add him as member but it got added to the group and he could see and amend all of my plans (projects). 

How can i do to only share one plan (project) to him? do i have to create another group and call it shared and copy the plans i want to shre into it and then invite him in that group? the only problem with that solution, it creates a duplication of data.

is there any other way to only share one plan but not all plans within a group?

thanks