I wouldn't - as soon as you connect them the cells will try to equalize and that may cause overheating due to high current flow. I don't know that for sure, but I'd be concerned enough that I wouldn't.

I would charge the one thats down rather than disch the one thats up, but it prob doen't matter, I just don't like discharging a lipo for discharge sake, I'd rather run it to get it there.