We are in the process of migrating our SFDC Opportunities into the Deal object in Hubspot. In this sense, "in the process of migrating", means we are creating the data model to map these objects.
It is not clear how we can automate the association between these imported deals and the existing contacts in Hubspot.
If this is possible, I'd assume that the process for linking these deals with Companies would be the same.
The Contacts and Account associated in Salesforce will be associated in HubSpot when the Import happens.
To do this, you navigate to Imports > Integrations > Salesforce > Standard Objects. When you import all standard objects, this will create the associations that are in Salesforce.
If you're doing this outside of the integration, you can add the Primary Contact ID as a property on the Deal and use Associ8 to associate the Opportunity to the Contact using the Salesforce ID.
How is the migration happening? Is it via an integration or with CSV exports/imports? If it's the former, the system should be able to take care of it. If it's the latter, when you're exporting the Opportunities from SFDC, ensure that the export has the associations with the contact emails, then when you upload those into Hubspot, you can upload a single file with multiple associations in one go.
It's happening via the Salesforce integration. In this sceanrio, are certain fields required to ensure the association? As an example, primary contact on the Opportunity from SFDC?