The idea of an involuntary "changeling" would put a wonderful spin, here, on the whole wizard/faerie tradition. Under this theory, then, when McG says that Shah "replaced" the Swithin girl, you mean literally replaced, within the Swithin family? Rather than that she took the available Wizard-family opening originally intended for the Swithin girl.
My first thought was -- wait, the Swithins refused placement. But maybe the scenario is like this: first, a family of Muggles is approached about giving up their magical infant. Then, if they refuse, a non-voluntary "changeling" action takes place at some point. When McGonagall notes that the Swithin family "turned the offer of sanctuary . . . down," she's not just sadly regretting a missed opportunity; she's euphemistically alluding to the fact that things got more complicated and potentially uglier. And then a moment later, she and Molly recall who the "mudblood brat" that Lucius had "removed" actually was.
Would Shah be a wizard herself, though? A wizard family's child, yes, but I was speculating below (http://community.livejournal.com/alt_fen/3354.html?thread=31258#t31258) that older children might be involved in a Squib-for-Muggleborn sort of swap. Otherwise the child would grow up and be exposed when it started manifesting magic. Or else, consistent with the "changeling" theme, it could "die" and be taken back into a wizarding family, but that wouldn't solve the problem of an extra child in the records, and it doesn't seem to be the model in the Swithins' case. Still, some variation of all this seems like a tantalizing possibility here.
Re: I think you're right!
My first thought was -- wait, the Swithins refused placement. But maybe the scenario is like this: first, a family of Muggles is approached about giving up their magical infant. Then, if they refuse, a non-voluntary "changeling" action takes place at some point. When McGonagall notes that the Swithin family "turned the offer of sanctuary . . . down," she's not just sadly regretting a missed opportunity; she's euphemistically alluding to the fact that things got more complicated and potentially uglier. And then a moment later, she and Molly recall who the "mudblood brat" that Lucius had "removed" actually was.
Would Shah be a wizard herself, though? A wizard family's child, yes, but I was speculating below (http://community.livejournal.com/alt_fen/3354.html?thread=31258#t31258) that older children might be involved in a Squib-for-Muggleborn sort of swap. Otherwise the child would grow up and be exposed when it started manifesting magic. Or else, consistent with the "changeling" theme, it could "die" and be taken back into a wizarding family, but that wouldn't solve the problem of an extra child in the records, and it doesn't seem to be the model in the Swithins' case. Still, some variation of all this seems like a tantalizing possibility here.