Merging 2 large CSV files for 1 Power Pivot analysis

Hi, I have 2 large CSV Files (600 MB+ each with over 2 million rows each) that I want to merge in excel for a single Power Pivot analysis.

Both files have the same structure and column titles. (each file has data for a different year)

I managed to create a power pivot for each file without issues.
I then tried to "create relationship" on the "design" menu for both datasets but got a:
"relationship between (...) is a many-to-many relationship which is not supported" error message.

Is there another way I can "merge" these 2 datasets this in excel?
(Excel 2016)

Thanks

I tried to see the query option but abandoned it when I saw that I had to load the data into excel.
Wouldnīt that make the query too big (over the supported row limit) ?

Using the query/data model combo option was indeed the answer:

After choosing the csv file on the "New Query" tab:
"Load to"
"Only Create Connection"
"Add this data to the Data Model"

After both files are loaded, on the "New Query" tab:
"Combine Queries" + "Ammend"
This creates a 3rd Query with the merged data.

The merged query can the be accessed with Power Pivot.

I donīt like the fact that it created a 160MB sheet, but it does what it says on the tin.