Dathai,
I think I've figured out how your great grandmother did it. She fed them both at the same time.
However, I haven't figured out Richard Donoghue. 9 Terrace Place features on the 1868 Wedding (of a widower with parents of the same names as the guy who was married in 1856 & whose wife apparently died in 1866), on the 1869 birth of daughter Marcella and on the 7 January 1872 death cert. Whether the person in the two marriages (1856 & 1868) is the same person or not, I believe that the Richard who got married in 1868, died in 1872. I think that my great grandfather Richard on the 1901 census is a different guy, suggesting that Mary Monahan & Catherine Monahan are different people. Or do you have a different take on the Richards?