<p>I was in a very similar situation (not so much involving a church, but i got a rec from a club adviser that knew me in a very different context than my teachers and expressed some of important abilities of mine in her rec), and i included a third rec. I think it was a good idea. </p>
<p>They discourage it bc, as this site proves, people tend to get crazy about their applications. If they didn’t strongly caution against sending supplemental recs, there would be that bonkers CC-er who sent in 25 supplemental recs. I think one good one that isn’t redundant and contributes meaningfully to your application is perfectly acceptable. </p>
<p>Also, i think it would be a bad decision to ‘save’ a good rec in case you get deferred. Your application, SCEA or otherwise, should be as complete as you can make it.</p>