Here's a positive suggestion. Instead of wearing the non-sanctioned DG crest pin, how about getting brother a DG themed tie, if they make them? I bought a Gamma Phi Beta tie for my dad at the vendor tables when I went to convention in college...it was really preppy with cute crescent moons embroidered on it. On the back, there was a label that said, "made expressly for Gamma Phi Beta Sorority". He really liked that tie and he wore it a lot when I was in college. Not too long ago, he said, "Hey, I wonder where that tie went?"
I bet he gave it to Goodwill and now some man with no connection to Gamma Phi is wearing it!!!