How to use a dropdown control to change multiple charts from different data sources?

[cc2025]

I have three different data sources that all have a date column. I want to use a dropdown control to filter all of my charts at the same time. I can't use Looker's built-in date control because I want to filter on month only and don't want users to be able to freely select days or go outside of the available month range. If I use the date from any if the data sources in my control, it's only going to filter the charts that belong to that one data source. So the only thing that seems to work is using Looker's built-in date control but that is causing mass confusion and frustration for users.

[Looker_Studio_B]

You may want to check these:

How to map fields from different data sources in Looker Studio? | Medium

 How to build a control that filters blended data in Looker Studio? | Medium

[lauratilton]

You'll want to create a Month-Year calculated field for each data source, and give all the calculated fields the same field ID (like MonthYear). Then you can set up the filter with any of those fields, and it will control charts based on all 3 sources.