They are three DIFFERENT orders. The ordinand receives the Mystery of Holy Orders for the Diaconate, then for the Presbyterate, then for the Episcopate.
I assume you take the position from St. Robert Bellarmine. Which is not supported by the Angelic Doctor, St. Bonaventure, St. Albert the Great, or Scotus. who write that the episcopacy is only an extension and complement of the priesthood.
The arguements presented by St. Thomas Aquinas, are as follows,
(a) The Sacrament of Orders is inteneded principally for the consecration of the Eucharist, for the Sacrifice of the Mass. But as far as the consecration of the Eucharist is concerned, a bishop or even the Supreme Pontiff himself has not greater power than that of a priest. Nothing is greater among the sacraments and in divine worship than the consecration of the Eucharist, because the Eucharist is the end of the other sacraments, in this it contains the Author of grace.
(b) the episcopacy adds to the simple priesthood the power of ordaining, confirming and governing a diocese. Thus the episcopacy, in what it adds to the simple priesthood, very probably is not an order distinct from the priesthood but is its extension and most perfect complement.
Fr. Regenald Garrigou-Lagrange the renowned Dominican Thomast, writes in “The Priesthood and Perfection”, pp 92-3, “This is confirmed by the Council of Trent, for in its list of orders it names only seven, and omits the eepiscopacy…”
in the next paragraph he replies to the objectin that the Episcopacy raises one to a special character, or another order thus…
“For this special power, it is sufficient that the episcopacy should be an intrinsic complement of the Sacrament of Orders. Thus, by episcopal consecration, a special character is not conferred, but the priestly character is extended in a real and physical way to higher functions, just as in the ordination of a priest the priestly character of consecrating is extended to the power of absolving by the words: “Receive the Holy Spirit, whose sins you shall forgive they are forgiven” … Very probably the episcopacy is not an Order stricly so called, nor a sacrement distinct from the priesthood, bu the fullness of the priesthood.”
Fr. Garrigou-Lagrange and others support the Thomast opinon that the Sacrament of Orders is just that, one sacrament, and not three distinct sacraments, while modern Sacramental theologians write that the Sacrament is composed of those men ordained to the Diaconate, Priesthood and Episcopacy, Trent and the majority of the writers, (that I have read, or have been mentioned in Herve, Prummer and other writers of Dogmatic and Sacramental Theology that I was taught in the seminary (I must admit most of the writers I read were published prior to Vatican II) support the position I was trained in, ie the deacon and priest share in the priesthood of the Bishop, who holds the fullness of the Sacrament. We see something akin to this in the position held by some Orthodox Churches who deny the validity of the sacraments of a priest who is not licensed to function by a bishop, the antimension being a visible sign of his ability to serve the liturgy.
While the position is not held universally, (St. Robert Bellarmin as noted above) it does seem to be, or at least prior to Vatican II have been the majority opinon.
Edited for typos, and not content.