Hey guys, FT newbie here

I have an upcoming trip to Southeast Asia from the states and apart from my booking from EWR to SIN I have a separate booking on Silk Air (which I did on SQ's site) for a round trip from SIN-MDC. I thought I'd be able to earn miles towards my OnePass account on Silk but I just got off the phone with a rep from SQ who told me that I wouldn't be able to. Is this correct? I thought Silk was in Star Alliance?

EDIT:

Realized I posted this in the wrong forum - sorry. I can't figure out how to delete this post.