How do I get a highlighter stain out of a white threaded badge/patch, that is attached to a navy blue blazer?

I literally JUST yesterday got the blazer that my daughter wears to her school on formal occasions, (private school, they wear uniforms). I got it back from my dry cleaner, and my son felt like being a little trouble maker and took a pink highlighter and put 7 dots all on the white thread around this circular patch that has my daughter's school Emblem sewn on. Its sewn onto the blazer too. The tread it sewn over many times on the patch itself, so the pink is quite noticable.

So if I use bleach won't it accidentally bleach the blazer too? I can't send it to the dry cleaners, I just paid for the last trip to the cleaners. I don't want to ruin it and I don't want to spend a lot.

I've never tries to get a stain out of thread before. The blazer says dry clean only, so throwing it in the wash is out of the question. HELP ME!