Apologies, I can't seem to find an answer for this in search.

I've got an award flight on NH coming up, ticketed by UA. I'm guessing I use the onlone check-in on the NH site, correct?

Also, I had a problem the last time I flew on a CO-ticketed NH award. I walked up to the NH check-in desk at PVG only to be told I wasn't on the passenger list. It wasn't until a couple minutes before check-I'm closed before they suddenly waved me over and told me my info suddenly showed up. Is there a way to make sure such an unappealing close call won't happen this time?
(I'm assuming that success at OLCI would mean this wouldn't be a problem, but if it doesn't succeed I'd probably take it as a first warning sign of this happening again)