DNS Hub for Google Cloud with Hybrid Design with On-Premises

I am new to DNS and Google Cloud. Here is my question. I am setting up a hybrid connection between on-premises and GCP. We are using disjointed domain names for DNS resolution. ON-premises is corp.example.com. All resources in GCP is gcp.example.com. Here is my question. For my spoke projects, do I only need to set up private zones in each spoke project (eg., spokea.gcp.exmaple.com, spokeb.gcp.example.com) ro do I also need to set up a private zone in the actual DNS hub itself for gcp.example.com? When I set up the the fowarding zone in my dns hub to forward all requests for corp.example.com to on-premises, do I need to set up a private zone for gcp.example.com in my DNS hub as well?