Classes of similar armor types should have other class tier lookalike sets in the Extra tab.

For example, warriors and paladins should have this DK set listed:

https://www.wowhead.com/transmog-set=505/magma-plated-battlearmor-normal-recolor

Every slot but the hands has a boss drop or BoE that all three plate wearers can collect.

I have confirmed you do not already do this with 11 random sets and the example above is not a one-off issue.