That's the problem right there. The Project task list isn't designed to be
outlined according to time. It's a WORK breakdown outline broken down
according to deliverable, the thing a group of tasks produces. For example,
if you were building a house your summary tasks might be "Lay Foundation",
"Erect Walls", "Install Roof", etc, where the completed foundation, walls,
and roof are the deliverables. Indented under "Lay Foundation" would be
"Dig Hole", "Build Forms", "Pour Concrete", etc - all the things you have to
do to make a complete foundation - and Project would calculate the schedule
when you should plan to do each one of them. The problem with using Week !,
Week 2, Week 3 as summaries is what would happen if a task runs late and has
to push over from one week into the next? There's nothing that would move
it from its original Week 2 summary to now make it a child of the Week 3
summary other than manually editing the task list. If you organize by
deliverable and what was originally a 12 week project has more work added so
it now will take 16 weeks, when you add the new deliverables and the tasks
required to produce them the schedule will automatically get extended out
however far it takes.
One crucial thing to keep in mind. It sounds like your boss already has
some notion that Task X will occur during Week 6 or whatever. But the dates
for tasks ARE NOT a user input into the project schedule. Rather, they are
the software's OUTPUT at the end of the task outlining and resource
assignment process. You don't tell Project what weeks tasks are scheduled
for ... it tells YOU what weeks you should schedule them for. Put another
way, you don't tell it the schedule, it tells you. Task dates are the
output, not the input.