Just as the crash time at 1:57 am can't be right if the call was made to the Uvalde Sheriff's Office at midnight, I'm also skeptical of the mayday report since it seems to come anecdotally from the notification of a grieving close relative. Unless we hear more, I'd guess that the stepdaughter's impression was from the Uvalde deputies when they said they got a call from an aircraft tracking center about an aircraft down late in the night.
NTSB investigator Craig Hatch did not know of any ATC communications when he gave his press conference, however he said he was still in the process of collecting the perishable data of the crash in his initial onsite investigation.