Sub task dependencies

[SL]

I use Project to manage many small projects within 1 Project file.
Each sub project is a summary task with sub tasks linked below it.

E.g. Main Task
Sub task 1
Sub task 2
Sub task 3

I set the durations of all 3 sub tasks and the start date of sub task 3. I
then want Project to calculate the start dates of the other 2 sub tasks by
working back from the start date entered in the last sub task.

When I change the start date on the 3rd task, I want Project to move the
other 2 sub tasks accordingly.

The project is already set up with all the tasks in so changing the Project
Finish Date means all the dates change which I don't want to do.

Does anyone have any idea how to do this?

Any help will be much appreciated.

Thank You

 

[Jan De Messemaeker]

Hi,

I'll tell you how to do, but before I wish to say I would never schedule a
project like this (working back from the finish date is an unfailable recipe
for being late, hence failur of the project).
Anyhow, that is then your problem
Link the tasks FS T1-T2-T3
Give T3 a constraint type Must Start On, he dte you want
Give T1 and T2 a constraint of "As Late As Possible"
Constraints can be entered through Task Information, Advanced or by
insterting columns such as constraint type and constraint date.

Hope this helps.

 

[John]

I use Project to manage many small projects within 1 Project file.
Each sub project is a summary task with sub tasks linked below it.

E.g. Main Task
Sub task 1
Sub task 2
Sub task 3

I set the durations of all 3 sub tasks and the start date of sub task 3. I
then want Project to calculate the start dates of the other 2 sub tasks by
working back from the start date entered in the last sub task.

When I change the start date on the 3rd task, I want Project to move the
other 2 sub tasks accordingly.

The project is already set up with all the tasks in so changing the Project
Finish Date means all the dates change which I don't want to do.

Does anyone have any idea how to do this?

Any help will be much appreciated.

Thank You

SL,
First your post doesn't mention anything about linkages between the
subtasks. Since you are expecting dates to move I will assume the 3
subtasks are linked in the default (i.e. finish-to-start).

Given the above assumption there are a couple of ways to get what you
want. Probably the easiest is to use "reverse scheduling". Go to
Project/Project Information. Set the "Schedule from" option to the
Project Finish Date. Then enter the desired Start Date of subtask 3.

Reverse scheduling will ensure that all tasks start as late as possible
even though the Constraint Type field shows "as-soon-as-possible".
Therefore, when you constrain the third subtask to start on a particular
date, all the other tasks will move to accommodate that date.

Hope this helps.
John
Project MVP