I have the marriage certificate for Samuel and Betsy, which I will send to Jan when I get back to UK. His father is shown as William Smith, nailer-deceased.
So we have Mary and Samuel with a father, William, tying up with the William who married Ruth Green and we have Emma with a father George. Like you I think this is George Jeptha.
There is a George Jeptha who was s of William and Mary (Cradley about 1808)
Halesowen records have a marriage of a William Jeptha to Mary SMITH in 1806.
Thre is a burial of a William Smith in St Giles garveyard in, I think, 1829.
There is another daughter, Anne, born abouit 1848 and any details of her might help

One inconsistency is taht Mary's father, William, is described as a Collier but Samuel's as a Nailer!
Hope this is helpful...H