Adding external drive

Hi folks i have a Tivo Roamio Model TCD846500 and another one (same model) that i want to know how to go about adding the internal hard drive to an external enclosure as a second storage for my existing Tivo box.

Can I get the steps to do it?

Also will adding this second drive affect any of my existing setup? I don't have any critical preference settings but I want to at least be able to still see all the recorded shows I already recorded.

Any help appreciated
Thanks