This would mean that he's also the father of Ewan O'Hara as well, but I don't know if John Cena is returning to reprise that role. (If I was in charge, I'd let the upcoming episode be Shatner's showcase and then bring them both back for an O'Hara family reunion - if Pops O'Hara survives his debut, that is.)
As the Toobworld caretaker, I'll be curious to see if Shatner's character mentions his own Dad; because as it stands now, I have a theory of relateeveety that says Juliet's grandfather was the chief of police in Gotham City. And that Jules chose to follow in his footsteps rather than her own father's.
I'm tempted to add Tim O'Hara, the Los Angeles Sun reporter who co-habited with an extraterrestrial humanoid during the 1960's to the family tree, but I hesitate to say that he was also a son of Chief O'Hara. It would be easier to make the claim that he was the son of Chief O'Hara's brother, thus making him Frank O'Hara's cousin. (Tim had a cousin Harvey and a great-uncle named Shamus.)
The age difference between William Shatner and Stafford Repp was a lot closer than appeared, but Repp played Chief O'Hara as somewhat older than he really was at the time.
Since the fashion sense in Gotham City was very conservative and a bit out of date, it might be possible that Frank O'Hara visited his dear old Dad at Gotham City police headquarters wearing a suit like this.....
But then again, being a con man, he may have avoided Gotham City and its Dynamic Duo crime-fighters at the cost of his relationship with his old man........
'My Favorite Martian'