Hi Don or others,
We have been on a similiar quest for Daniel Mahoney / Mahony/ Marney as I have also traced back to Leah Shrimpton. I guess you found that there was two Daniels on the Mary but both are too old to be the death certificate in 1876 at age 71. I also tracked John / Daniel Mahoney on the Florentia and Daniel Mahoney on the Hercules.
Have you gotten anywhere on this puzzle?