Need Assistance with Subitem Dependencies and Scheduling

We have a large number of small projects, roughly 5-6 weeks in scope. I need to setup the project with a kickoff item and a deliverable due date. In between these two items I need a timeline for three separate departements, each of which has a list of sub-item tasks.

Ideally I would be able to change the status of the kickoff item to “Kicked Off” to set it to today’s date, manually set the deliverable due date based on the project needs, and then have the intermediate departments and tasks automatically fill out the timeline between those dates. Once set, I need to be able to adjust the deliverable timeline forwards or (rarely) backwards.

Right now I have dependencies setup to manage some of the scheduling, but cannot get the timelines to interact correctly. I have tried both Strict and Flexible dependencies, and strict gets me the closest.

Do I need to setup a start date (kickoff) and a “due date” as separate items, and then run all timeline adjustments via automation? Any assistance is appreciated.