So we're looking into how to build that via the API. I took a look at the companies and company properties endpoints, but didn't find any information on how I would be able to see, if a company is part of a parent/child relationship.
It would be awesome if someone would help me to find the right path here! (and if roll up reporting on contacts and deals is already natively supported and the knowledge base is just outdate, please also let me know
It's not currently possible to access parent/child company information via the API. This is something the team is looking to build, though I don't have any timeframe on it at the moment. Check out the topic below for some additional info, and check out the Ideas Forum on the HubSpot Community to give your support to this idea.