Tooth fairy identity

The day before her seventh birthday, Madeleine lost her first top tooth, one of the thibilanth. Now there’s a big gap in the top and she has the cutetht lithp.
Before going to bed (she was obviously excited about the upcoming bonanza, so the whole thing was an extended ordeal), we had the following conversation (among many go-to-sleep-I-can’t-I’m-too-excited exchanges).
M: Daddy, do you think the tooth fairy is a boy or a girl?
D: I don’t know. I haven’t really thought about it much. What do you think?
M: I think it’s a girl.
D: You’re probably right.
[several minutes pass]
M: Daddy?
D: Yes?
M: I think the tooth fairy might be mommy. She’s always tired in the morning.
D [trying to hide panic]: No, I don’t think so. I think I’d notice.
[pause]
D: Wait, you mean that mommy is the tooth fairy for everyone in the whole world, don’t you?
M: Yes.
D: No, I think I would notice.
M: But maybe she puts pixie dust on you to make sure you don’t wake up.
D: Hm. Maybe.
[whew]
Of course I told Julie about this (and had to clarify that Madeleine means she’s tired on weekends, because she doesn’t see how quickly Julie flies out of bed on weekday mornings, etc.). And apparently Madeleine had suggested to her that the tooth fairy is Mrs. Santa Claus, since she obviously knows where everyone is.