There's some good advice in there for sure.
Personally, I would feed them on a 10-18 day schedule (basically, shoot for 14 days and if you get to it sooner or later, it's cool).
I'd feed smaller rats than they can take for the first few meals just to ensure that their digestive systems aren't out of whack (no regurge and normal poops are what you're looking for). Then, after 4-5 meals, step them up to rodents that are equal to their girth.
After 6 months on this regimen (based on your weight description), they'll be robust, healthy animals again and then you can taper the feeding schedule.
Prior to that however, I'd be soaking those animals every other day for about 15 minutes. Not only will they absorb some of the water, they'll drink it too. As with people, dehydration is worse than a lack of food so you'll want to address that first. Keep soaking them on this schedule for about 2 weeks (more if you think it's necessary).
I'll tell you why I recommend the feeding schedule above. After gravid female BCC deliver their babies, I'll feed them a normal sized meal every 14-21 days and in 12 months, they're ready to breed again. And these are animals that are 6-7' long and had a pre-breeding weight of 10-14 lbs and a post-breeding weight of 4-6 lbs (MUCH skinnier than what you're reporting). The reason I space out the feedings like that as opposed to cramming as many meals into them as I can is because muscle is much more important than fat to a captive boa and shoving a meal down their throat every 7 days simply packs on fat, and not muscle. Fat boas die MUCH sooner than lean, healthy boas (fatty liver disease, hearts encased in fat, etc.).
So, take it easy with the feedings and in no time, they'll be in tip top shape.
jb
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What's written above is purely my opinion. In fact, MOST of what you read on the internet is someone's opinion. Don't take it too seriously 
Jonathan Brady
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