You still need to initiate having a credit file with D&B.
You may deal with only businesses that report to D&B, but if you haven't paid to have a credit file, then there is no file in which to report the credit.
There's no way around that.
D&B makes money by having the service, and they won't allow you to have a file just because a business is trying to report your credit to D&B.
If it were as easy as you suggest, no one would ever pay D&B the fee to have a credit file. They would just deal with companies that report to D&B.
