Is it legal for cops to question a four year old child without an adult or attorney present?

My SIL,"B" overdosed last year,leaving her four year old daughter.My mother in law has been taking care of the baby"M" for sometime before the death,because of allegations of ual abuse & neglect.( Long story short-"B" and a brother of hers were adopted by my MIL & now deceased FIL.Adopted came from ual abuse background,too).At "B"s funeral,the "father'-which hadn't been around since the birth of "M",showed up,only at the encouragement of "B"s former family-I think to get their filthy hands on the baby-fresh meat,sad to say. My blood BIL and his wife were trying to adopt "M",(MIL has permanant custody,but 65 and not healthy),but the former family of "B" has acccused this man(a very good,decent man,who actually lives four hours away) of abusing "M".To try to prevent BIL & wife from adopting "M",and hoping the excon 'father' will get her-he's also mentally challenged,BTW.Cops came in,took the child to another room and questioned her.Is that legal without an adult in the room,too?