MG seed-saving - newbie needs help
I know a lot of you on here know a lot about MGs, so hopefully you can help me out.
My 8 yr. old son has been planting morning glories for 3 years now, and this year he has suddenly gone a little crazy with it. His first year he planted Crimson Rambler, which I understand to be I. purpurea, second year, let those self-sow and added Scarlett O'Hara (I. nil?), and let those self-sow, third year added Grandpa Ott's, Heavenly Blue, and the Burpee mixes Early Call and Celestial Mix. His Scarlett O'Hara's and Crimson Ramblers came true with self-sowing up to now, but I am not sure they will after this year's bonanza of so many different varieties all planted in a fairly small area (about 100' x 30'). I have more space I could let him have, but this is still only a relatively large, small-town city lot - does have some barriers, like a 6 ft. privacy fence in back, if that would help.
He is saving seeds like mad, including some of I. hederacea and I. pandurata from grandma's farm, and wants nothing more for his birthday than a "big box of morning glory seeds" of types he doesn't have. I don't want to spoil his fun, but how in the world can he save seed and have any of these come true anymore? I don't really know which species will cross-pollinate and which won't, so any basics on that would help for starters. Other than that, can you give a little kid any advice on how to go about making seed-saving work for him? Oh yeah, AND he wants to try crossing some - I said I think the bees are probably taking care of that for us as we speak...
Hope this is somewhat clear, and thanks for any advice.