Using Orbi RBK30 and Satellite with Other Routers in our Home

I have an AV distribution system in my house - 8,000 sq ft. We have on modem that is in our basement. The ethernet in the AV distribution system distributes ethernet to 12 zones in our home to four different routhers for wi-fi. We were planning on trying Orbi in one of the large zones. I was going to simply plug the orbi into the back of one of the ethernet switches attached to one of the routers in one of the large zones. It would appear that using an Orbi plugged into one of the switch ports for that area would only be used as an Access Point and the satellite would be wasted in that large zone. Using only one Orbi, as one roams into the futher regions of the house, a person's phone would need to pick up the other network I would assume. First, are my assumptions correct? OR, is it as simple to set up one Orbi and Satellite in one large zone hooked up to a distributed ethernet switch coming from my A/V distribution outlets? Lastly, if true you can only use Orbi as access port - is it worth it for that area only as an Access Point? Helpless in New York!  Kirk