Hello Everyone

I am working on a project with it's initial completion date of 16th of June 2017. The project got an extension of 12weeks making the new end date to be  8th of September. 

My question is, and would be open to any suggestion; where in the plan should the 12weeks be added. The planner and I have different idea as i believe the 12weeks should be the new timeline for the rest of the project, but he decided to add the 12weeks to the last 3tasks in the plan. 

Please help guys. 

Thanks

'Kemi Banjo