Disclaimer: I don't have much recent experience sailing (crewed for a couple years 25 years ago, sailed a couple time recently, incl. on ASA 101 and 103 courses), but...
ISTM the child was safer down below, on the sole, probably, than up in the cockpit with all that tacking going on. Probably would've been best to call out "prepare to come about," etc. as you maneuvered, so she could prepare herself. I assume everything below was securely stowed, so there wouldn't be things flying around.
I am surprised she wasn't already wearing a PFD. Were you guys wearing yours?