https://docs.bigcommerce.com/developer/docs/beta/b2b-edition-beta/api-reference/company/post-companies-company-id-attachments
Add Company Attachment | BigCommerce Docs
Each company can upload a maximum of 10 attachments. The API rate limit is 15 times/min per store. The attachments support the following file types:
add company attachmentbigcommercedocs