I certainly wish that our purse-proud brethren, who lazily sigh for the ease of England or Germany, or the oblivion of the steppes of Russia, in order to escape the duties which God has imposed on colored men in this land, could visit your home and your office for an hour, and witness the devotion of all your family to the success of your paper -- which is the success of the cause also -- one lad setting type, then folding, another feeding your new press, and Miss R.D. just budding into womanhood, laboring with pen in hand, by the side of our earnest and most efficient English benefactress - and the editor himself so selfishly proud and so superbly ambitious, in his shirt-sleeves, driving the press!
"Miss R.D." is, of course, Rosetta Douglass, Frederick's oldest daughter, who was fourteen at this point. He had a younger daughter, Annie, who was at home with her mother and Aunt Charlotte Murray, being only four. The young men working the press were Lewis and Frederick, Jr., ages twelve and ten respectively. Charles, who was eight at this time, remembered that he joined them when he turned ten. The "most efficient English benefactress" was Julia Griffths, who was most important in ensuring that this paper continued production.
This scenario fits with the reminiscences of all of the Douglass children, and one of the sons did mention that their father, at the urging of Anna, trained the boys in printing. Frederick had begun his business with just such a goal in mind, not just for his own children but also to apprentice young black men who would have no other opportunities to learn the printing trade. In doing so, he would also help develop the black press.
Little evidence exists about Rosetta during this period. I found entries concerning her aid to fugitive slaves in the Rochester Ladies' Antislavery Society account books in 1854 and 1857. Between 1855 and 1856, she attended Oberlin's Preparatory School, probably to gain enough education to become a teacher, which did not require a college degree at the time. She taught in Rochester in the 1858-1859 school year, a change that coincided with Frederick Douglass' Paper's conversion from a weekly to a monthly publication. In late 1858, too, she worked on a convention to protest the execution of Ira Stout, and she almost went to Haiti with her father in 1861. The war kept them both in the U.S.
She asked her father to look out for an opportunity for a teaching position for her while he was on speaking tours, an ultimately went to Philadelphia in search of a job there in 1862, and found one in Salem, New Jersey later that year. When her brothers Lewis and Charles went off to war, she returned to Rochester. Then she married in 1864.
There is much more to her story, but this excerpt from this letter as well as its context show that she did more than prepare delivery, as she said in her own memoir.