Your tenant will have his or her own CPH on the land, I would think. Ex-BH had one CPH which covered land he owned and land he rented, plus another CPH on another parcel on which he had an annual grazing arrangement.
It's possible to have two CPHs on the same ground, managed by two different farmers. A dairy farm where I used to buy calves rented out his fields for winter grazing for sheep. The sheep farmer had his own CPH for the ground. I always thought it both bizarre and sensible that I could buy calves irrespective of the sheep's movements - since the sheep were only on when the cattle were housed, it was actually sensible that neither farmer's movements affected the other.
Of course, I'm talking England, and I don't know which country you are in.