You should be able to through-check your bags, but give yourself plenty of time since it's apparently quite difficult to check bags across PNRs if both are on United (it's easier for *A partners). You need an experienced agent to so this. (Just noticed that ORD-HND is on NH, so that definitely helps.)
Officially, you are not protected across PNRs, though United is pretty good about helping out in the case of irrops.