Okay thanks. I'm going to get compression sack for their kelty's synthetics. My youngest carried a standard school LLBean book back and got his bag in it with just the stuff sack. According to what you say i'll assume the jet 12 is smaller than a standard bookbag and i'll be assuming the jet 18 is closer to the standard size.

I appreciate the help.

My only other idea was to buy a smaller camelback hydration pack (since they are smaller in size) and attach their sleeping bags to that externally.