Updating phasing profile

I've got a project start date and end date and the phasing of the project. Everything is in fiscal year, that is, the year ends in 09/30 not 12/30. The project will always be 78 months.

Now, I also have a second project start and end date (starting on line 7). The phasing above it is the original phasing. What I'm trying to do is to find a function that will adjust the phasing when the project start and end dates change.

Thanks guys.