How to create a task whos duration is the time of a parent task

[EricSa7]

I have a task that has four sub-tasks (5 in total)

So task one = Parent Task. 

Task two is a sub-task of task one and has a duration of 2 days. 

Task three is a sub-task of task one and has a duration of 2 days and is dependant on task two ending before it can start. 

Task three is a sub-task of task one and has a duration of 2 days and is dependant on task three ending before it can start. 

Thus, at this point, task one has a duration of 6 days. 

I now want to add the 5th task, which is also a sub-task of task one, to start when task two starts and task three ends. Thus if task three was changed from 2 days to 6, then this task's duration and task ones duration will increase to 10 days. 

This sounds simple, but for some reason, I am finding it difficult to see how it is done. 

Help please - and thank you. 

[Doug_Den_Hoed__AtAppStore]

Hi @EricSa7,

One approach (leveraging the techniques from this Going The Extra Milestone post) would be to make Task 5 the parent of two zero duration placeholders (eg Task 6 and Task 7) and tied "cleverly" (eg Task 2 Start-to-Start to Task 6, and Task 3 Finish-to-Finish to Task 7) to achieve the derived duration you seek on Task 5.

For best results, I'd also suggest you review our Recalc Helper solution (especially the videos) as you think through the best time and ways to keep your workplan dates current.

Regards,

Doug