I think its a goo possibility I heard that 3 came originally.....I only KNOW of William and Joseph.
William's Death cert says born in belfast ireland to isaac and Margaret Hull......he was born in Dec 1847. His arrival date in the usa says 1869.
Joseph's death cert just states born in ireland no city mentioned but to the same parents he died before the census' that showed the arrival dates started being used.
Do you have any old family photos? We can try and compare joseph's son Joseph franklin to old pictures you may have to see if they are similar....
Your John though would be a middle brother in comparison to mine...Joseph was born in 1859 Ireland william was 21 when they left ireland Joe only 10 yours john if he is their brother would have left at ages 13-16. email me with your email and ill send the pic I got of my great grandpa Joe F son of Joseph...and see if their are similar facial features or not.