Did you notice that on the web page you gave it has John Ballentine Sr listed as the parent instead of George and Letitia. I feel sure it should be George and Letitia.
If you go to the Marliin Family Forum and start with message 17 there follow 17 resposes.
It appears that Letitia's parents are Joshua Marlin and Agnes McCullough. I read through all of the messages but didn't write it all down. But one of them says Joshua had 18 children.4 sons sons are listed in different msg who would be Letitia brothers although one person said he didn't have one of them listed.
There are 2 birth dates for Letitia one is July 16, one july 18 both in 1794 and I think both were given by the same person.
According to postngs Ralph Marlin (Joshua father, Letitia grandfather) came to Pa from Ireland, one states in 1730. two birth yrs given 1708 and 1707.
There is more including some military informationn. I think you would find it interesting.