How to link a user on the site with the name of the counterparty in 1C in the database?

Question

1C-Bitrix

We have a closed authorization system, only for certain known buyers.
Therefore, all users on the site are already registered.
After authorization, the user adds the product to the cart and starts shopping. At the beginning of the registration of the selected goods, the user is again asked for - Delivery date - Name - Email and - Name of the TT.
It is necessary that the site independently associate the user profile with the existing name of the organization and its E-mail in 1C and, after making the purchase, synchronize it with this counterparty in our 1C database.

Answer 1

Add the TIN field to the user profile, on the 1C side, synchronize using this field.