DN: A beneficiary in a Doctoral Networks proposal wants to enroll their PhD candidate in a PhD programme at another organisation which will not be a beneficiary in the consortium or participate in this project in any way. Is that possible?

A PhD candidate can be recruited by the beneficiary but enrolled in a PhD programme at another institution that provides PhD degrees, but that institution needs to be a beneficiary or at least an associated partner in the consortium. See also the Doctoral Networks Guide for applicants, page 7.