There is a tree On FamilySearch L21M-L7R which has all your names but I think it maybe yours so I don't want to duplicate the information, please can you confirm. It says Mortimer David was born 3 May 1862 Rochester, Monroe, New York but the records for Monroe did;nt start until 1880...
ok, you've got more confused now, which is'nt difficult ;). So are we discounting Thomas Mitchell and Isobel all together? Can you post any confirmed facts and documentation that you have and then we can work back from there.
Found David and his 2 siblings in 1851 all step sons to James Morton and Isobel so she did'nt die in 1849. She re-married in 1850...
ISOBEL JAMIE/FR355 (FR355)
Sorry if I seem to be going round in...
I still think the 1845 birth is the right one, you mentioned in your OP that Thomas Mitchell and Isobel maybe his parents, where did you get that information from? Looks like Thomas died in 1849....
These maybe him?
This matches the birth of David found earlier...