This is a problem. Some may be related and some may not. Genealogy is not as simple as we would like it to be. There is a lot of detective work involved. There is a lot of cross examination of the records.
Details mean a great deal.
Moving - This can also be a challenge, even to the trained and skilled professional. Especially if the family lived near a major river such as the Mississippi. The family could have either moved West for gold or North or South along the river. This also applies to immigrants from other countries. Many immigration records state where the family left from, but usually that is just the city of the port where they left.