UNION function inside one cube

Hello community, I need to solve a complex but trivial issue.

Given:

Two tables "Comment" and "Post". Each one contains an "Author" field, which is essentially a user ID. In these tables, each user ID represents an author. The goal is to count all participants together and then group them by month, language, and other metrics.

The question is how to do this within the IRIS ecosystem. Is it even possible to take two tables, get distinct data from them and then combine into one cube?