No, you're arguing against the evidence: in the faerie-tales, children who are bargained-away like that don't have the Faeries (when they come to take possession) dance around the issue or ignore it.
There is evidence, 1) Margaret did make a bargain of some kind regarding Harry. 2) While she made it of her own free will, the fetus, the future Harry Dresden, didn't. Mab needed Harry to agree of his own free will to be her Knight, even though he absolutely did not. However all through the first part of the series Mab was pretty confident that eventually he would. I think in Changes the reason Uriel intervened like he did just wasn't because of what Lasciel did,pushing Harry to suicide, but because technically it wasn't just her, but Mab who violated Harry's free will. Yes, it was Harry's choice to become Mab's Knight but it was the least bad of a number of bad choices to save his daughter. Uriel helped him make that choice as well, then Harry chose to die once his daughter was safe rather than become Mab's servant. Enter Uriel again with his seven words, words asuring Harry that he still had free will. In my opinion hinting at a loop hole that will eventually enable Harry to get out from under the Winter Knight's mantle.
Sometimes they can be tricked, or further bargained-with, but they come in clearly asserting their claim. That Mab did not do so says there was no such bargain.
No, it doesn't, Mab isn't stupid and she knows Harry, if she made that claim, it would backfire on her.
