Q: Log in difficulties for icloud acct set up for a child

I set up an icloud acct for my under-13 child -- so that we can use Family Sharing. Thought it was successful, but now can't login or retrieve pw. Think maybe I miss-keyed the bday -who knows - but is there a way to retrieve it? Won't accept my or my daughter's bday in order to get to security ?s. When I use the email option, nothing comes to me. (I was under the impression, this would somehow link to my acct - for this purpose - since it didn't ask for any other recovery info.) Any advice out there??