Most people sadie, will think your theories several pence short of a pound coin.
Now, as you haven't spelt out your theory, but if if's anything likes nessling's, is completely skew whiffed, and can be challenged even at a basic level. Now for example, as you believe in abduction, why didn't an 'abductor' take Madeleine's younger sister, who was smaller , easier to carry and had the same genetic bloodline as her older sibling ?
I have never speculated that they took her for her bloodline, although I suppose that is possible.
My thoughts are that she was abducted as a pretty vivacious little girl, probably for nefarious reasons
But I am thinking they then found that she was from a certain [probably noble] bloodline group, their own in fact ... and they were forbidden by their own bloodline rules from harming her.
I think that in many material ways she has been well looked after. And I hope so.
Please do not interpret what I have said incorrectly.