Ability to Modify Internal date of sub-releases to a Master Release Merged

When using Master Releases, the sub-release inherits the internal date and external date. Can we have the ability to modify the Internal Date of a sub-release that is attached to a Master Release? I have attached two images that would be an idea of what I would be looking for to provide high-level depiction of what is getting done when. The ideal would be leveraging the Internal date from a sub-release (sprint).

As a Master Release is really an epic of many product releases, this would help articulate when things are being completed. We are currently running sprints in our teams that are working to deliver code that launches on the Master Release due date.

If I have a Master Release that is going to encompass 7 weeks, we will have about 3 sprints (sub-releases) associate to them. However, each sprint will have the same Internal and External Date that the master release has; which causing confusion to those looking at the roadmap overview.

NOTE: There are probably other ways to update this but this for example purposes.