If the blood of the star does as you say, why did the witches not just absorb it in the same manner, rather than eating it? It would save them all the trouble of having to always find hearts or become old by using magic. This does not make sense to me.

I really love this story! You wrote it very nicely! It is so hard to find Stardust fanfics, and this is by far the best! Please please please update asap!