9 – How to index only end dates in the aggregated field in the search api?

I have two date range fields on two different content types. I want to index only the end date of both of the date range fields.

I can do it by simply clicking the plus icon on the field and add the end date only.

enter image description here

But this is not possible in the aggregate fields. In the aggregate fields.

I have a union on both date fields. But there isn’t an option to select the end dates only?

Is it possible to index only end dates from both the fields in one field as aggregated field? (