Like I said, I don't know which Stephen Abbott that your Ariana Oakley married in 1850 either...but, there are a few tips that I can give you. If you have a headstone or death or burial record, you can determine when he died and hopefully his age at death will tell you the year he was born. This could let you know which Stephen Abbott especially if there is 2 or more years separating their birth. keep in mind that sometimes they may be off by a year or so, because sometimes they count the same year of death in their birth even though they haven't had their birthday yet...Another great thing to try is what I call Generational Names..that is, see what names were carried down through the generations. List all the names of children of your Stephen and Ariana Abbott and compare them to the names of all the Stephen Abbotts and Ariana's siblings, their grandparents and their aunts and uncles great-aunts and -great uncles, etc. An uncommon name in the family is a great indicator if it is carried down. You should then be able to determine who has the most matches and the one most likely to be your ancestor. I had to do this with an Amelia Russell. Me and another lady had Amelia Russell in our tree...mine married Jonathan Abbott, hers married Henry Dawe. Both Amelia's were from Bonavista, and both born a couple years apart. First we thought there was only one Amelia Russell, until we found another one baptized in the Methodist church to the parents of one of our Amelia's. But, which Amelia belonged to who...we fought over headstones, births, deaths, and we switched back and forth several times until we did this family name thingy. When we did this, we found that one Amelia Russell's ancestors names matched almost perfectly with all the names of Jonathan and Amelia Abbott's children, and a lot of the names of the other Amelia Russell, although not as perfect, matched Henry Dawe's Amelia. We we tried switching our Amelia Russells, we found either no matches in names carried forward or just basically the most common names, so then we knew, and agreed that I had originally had the right Amelia Russell and she had to switch to the other one...lucky me, I guess...lol.
That Generational name thingy is how I come to have my list of Abbotts that I posted earlier. I also have a Russell list because of it. I had to do this Abbott list, because not only did I have a problem with there being 2 Amelia Russells, but I also had a problem with her husband because there were also 2 Jonathan Abbotts. I kinda knew which Jonathan Abbott was mine because of what my grandmother told me years ago, but I needed to prove her right and did.