I'm looking at UA881 from BOS-ORD-NRT as part of an upcoming award. ORD-NRT has C availability as per the ANA tool, but BOS-ORD only has Y. I've never used a 1 Coupon, Multiple Sector flight in an award before. I obviously want the C seat for the longhaul segment, but I don't care if I'm stuck in Y getting out to ORD. Does anyone know if I'll have to ticket this as two segments or if you're allowed to commingle classes on single coupon?

I'll be redeeming on US, and I know they're generally more flexible, but I will be bumping up against the max segment limit (4 per direction).