If these companies already exist in your HubSpot Portal, they do have an ID that you can find when you click on View all properties on a company record and then look for Company ID.
You could create a filter with the companies that you want, then export them - it would give you the Company ID in the CSV file. You could then import the file again with the new information.
Update companies with no ID in import - Any advice ??
Thanks for the reply, but not working in my case.
I did import the file anyway with no domain and only names. Do you know if Hubspot company enrichment can help and the dedup company system check on those companies?
An export should give you companies ID, if they don't would you mind reaching out to HubSpot technical support as it is going to need some more troubleshooting specific to your account? If you are having trouble contacting technical support let us know!
Regarding your other questions, the only other tool I could think of that could help would be our tool to manage duplicates companies in HubSpot, you have more information about that here. It would be manual however.