Suppose the buyer purchased fruit already on a tree, but before delivery additional fruit developed and became indistinguishably mixed with what was sold.
The new growth was not necessarily part of the original sale: it did not exist at contract formation. Hanafi commentaries discuss how inseparable mixing obstructs delivery and may affect the sale in particular circumstances.
This is a commentarial extension, not a new sentence being attributed verbatim to Quduri.