I’m not saying this is an acceptable solution, and it definitely needs automated, but, you can do this yourself, by exporting all your “stray” contacts and a complete list of companies. The contact list should include Contact ID and Company Name, whereas the company list should include the Company ID and Name. Match them in Excel using the “Name” / “Company Name” fields as the unique identifier, and reupload them into Hubspot in a doc containing both the Company ID and Contact ID on the same row. Hubspot will associate the contacts to the companies during the upload.
Time consuming, yes, but if you do this once a month or once a quarter, it’ll keep your portal from growing arms and legs.