Dev Started Date on Master Releases Reflected in Sub-Releases Merged

In the description, the point of master releases states:
Master releases are used when managing a suite of products that are released on the same date 
One of the things in this company is that they have multiple product areas that ALL follow the same release date. Using master releases is a good way to get the releases into those product quickly.

One thing I do believe is missing is the ability to set the development start date. I get the development may start at different dates but in some orgs, all sprints start on the same day and conclude on the same day, meaning dev start and release date across all products happen at the same time.

It will be good if development start date can be set at master release level and when creating a sub release, this values flows down into the product the sub release has been created for automatically, rather than having to go into each release for each product and apply the same start date. Either this or allow for bulk edit of start date for releases.