You can integrate them via Federation at the NSX level. Though, if that site is destined to become a vCF based deployment you would need to deploy it as a management domain. Keep in mind, mgmt domains are only performed by the Cloud-Builder from my understanding. vCF deploys workload domains. 

VCF is a private cloud with a bundle of VMware products (vSphere, VSAN and NSX-T). either it is standalone deployment or consolidated.

so the first workload domain which the management come with NSX-T deployed. and to connect with any NSX-T available in different environment you have to use the NSX-T federation.