I require two levels of task tracking - background is as follows

We have agreed on some fixed milestones/deliverables for various types of projects that each manager needs to strictly adhere to. For e.g. in Large development and deployment projects there are around 15 key deliverables managers should not temper with and should report timelines for them in that format. as in Business Justification, BRD, FRD, TSD..... These milestones/deliverables are useful for us in aggregating the dates in a standard format and monitoring progress.

 This task sheet needs 4 levels of baselining, one at initial stage, second after BRD, third after FRD and fourth after technical design. Not interested though in assignments etc

At the same time from usage of system perspective, and getting benefit out of Task / Milestone alerts etc, as also PMs having flexibility to define tasks underneath etc. I want them to have another task sheet where they can define as they like and assign it to respective members s.t. calendars, reminders, timesheets etc can pop-up.

 How can I achieve this - (am sure all orgs must be having requirements somewhat like mine)

Ok, I see two issues here, Task Tracking and Baselining.

Many companies report on the milestone level and track to the task level.  Your reports and views can be set up to show the milestones and you can make assignments and get updates on the task level.  If you don't set any constraints, your milestones will follow the same pattern of falling off of the baseline as your normal tasks and you can manage the tasks/milestone back to your original baseline. 

Why so many baselines?  I would start with an initial baseline (set up automatically now by Daptiv) and then snap a second baseline as you complete technical design and freeze your scope.  Anything after that point calls for a change request and can be tracked from this point.  Baselining at BRD and FRD just makes more management for your PMs when they are managing against a moving target.  Your estimates will be in the lower % accuracy when you start your projects and at a high % of accuracy after the final design.  Your PMs should be able to manage to this final baseline + approved changes.

Many thanks John, I think you got my problem well. Is there a way to restrict project managers from changing these milestones ? or add new milestones (based on suggestion to create a view/report).

 At the end of the day I have broadly 4-5 kind of projects that we run (we are on buyer side of technology, not an IT company)

a. New application deployment (no development)

b. New application development

c. Enhancements to Existing Applications

d. Enhancements involving Integration between existing applications

On baselining, since my costs include hardware costs etc, baselining at start is quite way off - involves multiple rounds of negotiations etc. - do not want PMs to build buffers and then have overruns hidden under those buffers.

 regards