Just a further update on this thread.

With the current volcanic activity currently happening, there are postings that have been reporting that flts from the UK are taking up to 2 hrs extra flying time to divert around the ash cloud. If this were to happen to my wife's flight next week she would more than likely miss the connection with me to Las Vegas.

After clearing immigration at ORD & before re-checking bags for domestic flights, is there a UA desk there that can take care of re-booking flights etc? I'm trying not to alarm my wife but I want to at least tell her what she might have to do if the worse were to happen.