Friends, I need your help!

Mapping account contact roles into account contact relationships

My Lighting migration has gotten stuck and I'm hoping someone out there has solved this one already.

'Account Contact Roles' are not supported in Lightning. 'Account Contact Relationships' is the suggested alternative. My challenge is mapping custom data from one to the other.

Please note, the issue is isolated to 'Account Contact Roles' records that are a direct (or primary) relationship.

Here's the steps I've taken. 

1. I enabled 'Account Contact Relationships'. This creates a record for every contact.

2. I exported a report of 'Account Contact Roles', which contained the custom data I wanted to map over as well as the contact ID and account ID.

3. Using Demand Tools feature Find Id's I attempted to match the contact ID and/or the account I'd of the exported report against the existing 'Account Contact Relationships' records.

4. No matches could be made, therefore there are no 'Account Contact Relationships' Id's to update.

That's a mouthful. Essentially, I expect that the records for both objects host the same account and contact ids, so I should be able to use them as matching criteria.

Has anyone tried working this out yet?

Thanks in advance...Sandy