I think I know the answer but I figured I'd ask anyway:

Is there any way to use the deviation funds from Sep and Oct to pay a single expense?

I'm traveling within the first 3 days of Oct so I can slide those expenses back to Sep. I've got over $1000 from Sep that's going to go poof. If my ticket is $2500, can I slide part of it ($1000) back to Sep and pay the rest w/ Oct money?