How to create a prompt, Year-Month format, in analysis while not having a "Month" dimension?

Summary

The goal is to enable end users to look at an analysis by year-month periods (ex. YYYY-MM, 2020-01), but "Month" dimension is not available within the subject area.

Content

Hello Oracle Community,

Do you know in analysis whether there is a method to create a Year-Month format (YYYY-MM, ex.2020-01) prompt without the availability of a Year-Month dimension within the subject area?  Condition displayed in enclosed screenshot.

The goal is to enable end users to view an analysis in different year-month periods by selecting them on a drop-down prompt.  In the subject area, the only date type dimension available is "Account Established Date", that comes in DD/MM/YYYY format.  Dropping this dimension in prompt section only limit selection to each event date, but not at a upper tier of "Year-Month".