Well with your footage divided amongst three separate sequences you can simply drag each of the three sequences onto the fourth timeline from panel that houses your bins, it will act just like a solid piece of footage.

Actually, I deleted the original three sequences after pasting all of the contents into one big fourth sequence, which I've been editing since. Now I need to break that one big sequence into three 50-minute sequences that will nest into a single sequence so I can edit each individually with the changes showing up in the big one, which I will eventually use for exporting the final cut.