Definitely keep us updated! I know I'd love to hear how they grow and develop, its always fun to watch bettas change over time, especially when you get them so young!
Hmm....you mean the tank is a half gallon and divided? Thats going to be a really difficult upkeep for two fish, even temporarily and even if they're little.....plus, I can't imagine even those little present heaters would fit in there. :/
Because smaller/younger bettas like the babys and small females they've been selling can be so much more sensitiveness and do need a little more care, it would be much better if you got them into something a little bigger ASAP.
Kritter/Pet keepers actually make GREAT tanks if funds are tight, and the medium-large size is big enough for permanent homes. If funds are REALLY REALLY tight, head over to Walmart(or a similar store)and pick up a couple of sterile plastic storage tubs. You can easily get a good 2-5+ gallons for very cheap, just stick a heater and some silk plants in there, poke a few holes in the lid, and instant cheap temporary/hospital tank! Not very attractive, but it'd definitely be better and easier for both you and the girls until you can invest in something bigger.
Aww, that little Delta guy was probably a marble! He sounds beautiful, but I know what you mean. I've passed up many a lovely betta for another; some just really call to you and you just can't leave them behind.
Ahh, that white boy.....it really is SO tempting to take you up on that offer.....I have a spare 5 gallon now, and I was planning on picking up a boy or girl on Christmas Eve.....but an all white(possibly platinum)dumbo HMPK.....UGH, I need more tanks...