... the entire theory is based on the words 'father' and 'daughter' and nothing more,
That's incorrect. The theory is also supported by the time discrepancy and the discrepancy over Sheila's age.
Not really. Yes they are discrepancies, but they do not indicate that Ralph called the police any more than they indicate that Kermit the frog called them.
....
Actually, there is no evidence that the details about the sender and receiver of these messages, related to any particular incident or event in it, since, if there were three or more events logged in the message form, timed at 3:26am, and two references in the other, now why couldn't all these different parts be documented in such a way as to leave little or no doubt at all, about who spoke to who, when and why, at different stages during that particular morning?