That makes it two separate awards. When you OLCI for your LAX-EWR flight, it probably won't try to check you in for your EWR-IAH flight. That flight will probably only be eligible for OLCI 24 hours prior to its scheduled departure. At that point, the waitlist will expire and you should be able to do OLCI. Historically, you could then add yourself to the upgrade standby list per your elite status. You would have to wait until you got to the airport to request that your position on the list reflect your mileage upgrade request. They were working on making that part of the OLCI process, but I don't know where that stands. There was a big thread about it a couple of months ago, got somewhat contentious. Thread started by belynch, IIRC, so you can search if you want.