When I first saw the blood thing in the KM, I couldn't help but think about how those diets work, like Weight Watchers.
Maybe they could simplify the whole process and assign points for each type of blood fraction. Then, if you had to receive multiple products derived from blood, you could just add up the total.
After totalling up the score, your trained conscience would then know, based upon the number, whether it is acceptable or not. It really could be like the Weight-Watchers dieting thing. Trade in some blood components one day for another, just keep the score under 100 or something.
Elders, MS's, pioneers and other with special privledges could earn bonus points based upon their time in the organization. A spiritually weak person that is irregular in field service may only be allowed to score an 80 or 90 in total blood points whereas the long-time pioneer sister may be able to exceed 110 or 120 before crossing the line into the unaccepable range.
Rub a Dub