Dependencies

Hi Kris, thank you for your question. I hope I've understood your question correctly. What I think you need to do is:

Create Task C and mark it as a summary task. Then create Task A and set a duration and start date. Leave this task as As Soon As Possible (constraint).

Afterwards create Task B and set the duration and start date. Then, set the constraint for Task B to Must Start On. (for this, double click the task, go to Advanced)

Next, select Tasks A and B and indent them. It might be better not to link them at first.

Task C will now be a black bar which will keep showing the combined duration of Tasks A and B, even if you make changes to their durations.

I hope this helps.

Kind regards
Marius Barnard
STL