NameSusanna Mertz 
Parent-Proof notes for Susanna Mertz
Susanna was listed first among his daughters in her father’s will. But neither Meiser nor Jack Mertz show such a daughter, on the other hand both do show a daughter named Margaret (Jack called her Peggy) not named in Peter’s will and who both say married Mr. Snell.
I cannot find any trace of Susanna Mertz, Susanna Snell or Margaret Snell in the 1850 Census. I just don’t know what happened to Susanna and I have no idea how both Meiser and Jack Mertz thought there was a daughter Margaret.
Research notes for Susanna Mertz
Meiser lists Margaret third and says she married Mr. Snell.
Jack Mertz lists Peggy third and says she married Mr. Snell.