Billing AND Site addresses for clients

I have quite a few clients who have multiple properties, so it would be such an improvement if there was a space for a clients "billing address" and "site address."
I find this so important, not just for my own client records, but for their business records. They frequently do not bill and ship to the same location, so there must be a reference to the property where the work is being done, which is separate from where their business is registered.