Thank you, Sherrie.I am having similar issues within my own family.Everyone seems to want to hang their hat on Robert of Londonderry b. 1714.I have since found that my ancestor does have a brother named Robert.At best, he was the BROTHER of my ancestor.
Documentation/testimonials about this man indicate that his father was the one who originally emigrated.They referred to Robert Mitchell's father as the immigrant, not him.There is also testimonial that the man was one of 13 siblings.How many of these emigrated?We only have record of two possibly three who descend from this Robert Mitchell of Ulster who emigrated at an undetermined time.Those two are Robert and Daniel Mitchell but what happened to the other 11 children?
How many people have been attributed to this man who could have been nieces and nephews and they have attached them to the wrong father?
I do think there may have been a connection to all these Mitchells back in Ulster.However, the researchers have to cross the pond, if you will, and look through a million vague parish records.I don't think there is enough surviving evidence to prove exactly where all these lines cross.I was in Derry in March 2012 and you need a handwriting specialist and a few professional researchers to unravel the records.Only a few have survived with very little information on them.Without knowing the exact parish of Derry you will never find the tie...unless every parish in Derry with a Mitchell surviving in it is tested.
I understand your frustration for I feel it myself.