Moving a supertask is not moving its subtasks, but it looks whether the 
subtasks 
still 
fit in the start-end dates of the supertask.
Unfortunately this is done in a non-atomic matter and after moving one subtask, 
the 
start-end dates are changed and all of the other task fit (and are not moved)

My suggestion it to reimplement the algorithm of moving (super)tasks by just 
moving 
the task and subtasks when they are not a supertask. This way all 
non-supertasks are 
moved, the internal mechanisms will update the supertasks and everything is 
moved!

I am willing to take a look at this, but I would like to receive comments 
whether 
this is a/the desired strategy not.

[deleted comment]

When I make adjustments to subtasks the parent headers do not adjust to fit the 
new start and end dates. Even after adjusting dates and using the drag feature 
to shift the end point. There seems to be a great deal of difficulty around 
readjusting start/end points.

See example mentioned above in the attached screen shot. Pro Box Parent would 
not shift end date to match the new milestone date. Even manual changes to date 
and using slide feature on the parent grouping did not work. It would always 
snap back to original date.

Milestone "Pro Box Review".
Full File. Not sure if the milestone having a duration of 7 days might be part 
of the problem but I can't seem to make any change to that range.

Nevermind. I kept messing with it and ofund that I have to actually go into the 
milestone edit datails - uncheck it as a milestone - adjust the duration (that 
was automatically greyed out) - then recheck it as a milestone. When I OK and 
return to the main screen the parent grouping (if that is actually what you 
call it) does snap automatically to fit the true start and end dates of the 
whole project. Either it should not gray out the option to to edit ranges in 
the milestone or it should automatically adjust to a 1 day duration since as a 
milestone. 

If we link predecessor task to only main task, Sub Tasks under that main task 
will not align properly within main task.

a) Sub Tasks start before main task start.
b) Sub tasks do not start at the same time of main task start date.

Please see attached photo and project files for more detail.

If we link predecessor to all individual sub tasks, sub tasks move 
automatically correctly within main task.

This issue was updated by revision 54c5ef8970a3.