Database too big

I have an excel database that is too large, over 500K rows and is becoming very difficult to handle. therefore I split this data in two files. I uploaded the two databases in PBI, but now how can I put then together so I can run the visuals based on the two sets of data?

The first data will remain static, but the second data will continue to grow, so eventually I will have to cut this data and create a third database, so the process will be ongoing.

Appreciate any ideas on how to do this