Unless there is an idempotent relation where \\( X \otimes X = X\\), in which case the wires naturally collapse into a single wire, one can place multiples of wires next to each other.

So far, there is nothing in the rules John has given that indicate you can't do so.

In fact, if you think about it, you can answer #9 by thinking of addition in this context as combining multiple ( non-idempotent)) wires that have the same label.