Using Mega and Uno together

Not sure if this is the right forum for this question, but is it possible to use an Arduino Mega and an Arduino Uno together on the same computer? Specifically, I will be taking 5 MAX31856 thermocouple amplifiers and I was planning on splitting them up between both boards.

Yes, absolutely, there are no specific issues with doing this.

That said, you could interface all 5 of them to either the Uno or the Mega (I don't know whether your application dictates the need to split them up)