Supplier Maintenance

Hi,

I want to know the best practices in  supplier maintenance in the following scenarios

1. when supplier changes address of a particular site then is it good to update that site record itself or create a new site and merge the old site into the new site?

2. when supplier changes the name then is it good to update the supplier record itself or create a new supplier and merge the old supplier into the new supplier?

Rgds,

-Kamal