It sounds insane that you need "rewards and punishments" for one human to be nice to another. Friendliness should be a natural by product of happy people in a good workplace.
I'd suggest a different tack, analyse what in the system has led to one person to be unfriendly to another, and solve it without assuming the buck stops with the individual as some type of perfectly free agent in a skinner box.
Proper pay, proper healthcare, leaders that lead by demonstration and treat colleagues with respect and a business that does not lead to angry customers by being scummy... are just table stakes for example.
I'd suggest a different tack, analyse what in the system has led to one person to be unfriendly to another, and solve it without assuming the buck stops with the individual as some type of perfectly free agent in a skinner box.
Proper pay, proper healthcare, leaders that lead by demonstration and treat colleagues with respect and a business that does not lead to angry customers by being scummy... are just table stakes for example.