Switch the date grain without altering the date range

What is the problem or goal the end user is trying to solve or accomplish?

When a user modifies the "Date Grain," there isn't a default mechanism in place to automatically adjust the date range as well

How are they solving it currently?

Changing it manually

What is the recommended solution by the Customer?

For instance, if you select a monthly date grain and set the date range filter to display the last 18 months, it will show data corresponding to that period every month. However, if you switch the date grain to weekly without altering the date range, it will still display data for the last 18 months, but every week this time. Would be useful to create a way so that when the date grain is switched to weekly, the date range automatically adjusts to show data for the last 18 weeks instead of the previous 18 months.