I'm not sure my answer applies, as I don't know whether the Episcopal Church teaches transubstantiation. But, if it does, you could refer to the Catholic Church's stance on the matter. I.E., Christ is fully present in both species, both in the appearance of bread and the appearance of wine. Hence, to receive either one is to receive Christ in fullness.
There is no Divine precept binding the laity or non-celebrating
priests to receive the sacrament under both kinds (Trent, sess. XXI,
c. i.) (c) By reason of the hypostatic union and of the indivisibility
of His glorified humanity, Christ is really present and is received
whole and entire, body and blood, soul and Divinity, under either
species alone; nor, as regards the fruits of the sacrament, is the
communicant under one kind deprived of any grace necessary for
salvation (Trent, Sess. XXI, c., iii).
I haven't read the article in full. But, from what little I've read, this actually seems to be a pretty controversial topic in Church history!