After considering many of the options, I think we should at the very least consider this about scions:
Does it have prerequisites: has bloodline (major or great)
And if so, as the character no longer has the prereqs for it, do they lose it?

Or, the other way we go, which is to keep the level(s). This is what Raesene values, and I think I side with him. It also keeps from having a major headache of converting levels... which sets a bad precedent as well.

Also, this is all very hypothetical - I have never actually seen a BR campaign with resurrection - but I must assume that ANY person that had a major or great bloodline will be out to get a bloodline back, through whatever means their alignment will allow... which means, keeping the scion level may be beneficial; because they may get it back.