I've been able to accumulate a lot of United Miles and United Super Saver TATL awards in Business are a sweet deal. However, I live in Las Vegas and I now find that while I can get what I want over the Atlantic in Business, for Super Saver award travel I can only fly between Vegas and Newark economy.

I'm actually willing to use miles for the TATL portion and pay for first class between Newark and Las Vegas.

Unfortunately, United will not ticket award and paid travel as a single ticket. I have called United and asked, "Suppose I use miles for award travel from Lisbon to Newark and then buy a separate non-refundable first class ticket from Newark to Las Vegas and allow at least 1.5 hrs. connect time as you recommend, but the Lisbon to Newark flight is late and I miss the connection, will you put me on the next available Newark to Las Vegas flight w/o a change fee or penalty?" United says yes. Can I rely on that? Advice would be appreciated.