need to assign one owner to many leads, but keep contacts with original owners, how?

need to assign one owner to many leads, but keep contacts with original owners, how?

hi, in my company i have 5 sales rep, each one made a lead from the same company, but each one has a different contact info, i want to assign 1 sales rep for each company, but i want to keep all contacts and with their original owner, for commission purposes, whats a quick way of doing it, step-by-step, thanks.