Continuity mistake: In Maggie's first fight (when Frankie isn't her manager), she comes off after the first round and takes her mouthpiece out. After talking to the manager, she gets back up to enter the ring without putting it back in, but when the bell rings she has it in again.
Continuity mistake: When Maggie is talking to Frankie in the gym bleachers, discussing Frankie's daughter, Maggie's ponytail keeps shifting from behind her back, to over her shoulder, and back again.
Continuity mistake: When Maggie is first shown in her hospital bed, you see her left eye is closed and swollen from the fight. Then, you see her left eye normal, then it goes back to swollen and shut. (01:33:20)
Answer: No, the cause of conflict between Frankie and his daughter is never revealed - we only know that she returns his weekly letters, and it has been some time since they have had contact.