Managing New Contacts and Company Updates Between Pipedrive and Clay

I am building an automation where new people in Pipedrive get pushed into Clay, what happens if they’re already in the Clay table? Also, if I am pushing the companies the people work at to a new table in clay, and I enrich the companies, what if I want to update all of the companies at a later date (say 6 month) and push them back into Pipedrive with the updates? This means the people and companies will also be in seperate tables, but both connected to pipedrive