Organisation to independant contractors CRM sharing

Organisation to independant contractors CRM sharing

I am an independent contractor doing business with various organizations. I use Zoho CRM but my main client does not at this time. I would like to be able to set them up so that we can share project/specific_contacts information. I do not want to discard my records but would prefer if we could share across my organization and theirs.
What would be the best setup and process recommended?