First off, save yourself a great deal of time and effort.You are already in contact with your cousin Margaret. She and I have been in communication regarding the family genealogy on the Stillwell/Stilwell side.Take the opportunity to review the research that has already been accomplished.
Once you start your other family lines take yourself out of the year 2010 and place yourself in the year or years that you are investigating.People didn't really "dance" around birth years, places, etc.Know the history of the period you are researching and understand that county and state boundaries changed over time.Though people lived on the same farm/homestead, the county boundaries may have changed and their records may be in two or more counties plus states as the states developed from territories.
Census records are as only as good as the enumerator and the perosn providing the information in a moment of time.It may not have been a family member who provided the information.Education levels varied based on the location of the farm/community in which families resided.Religious associations varied based on what religion the available minister was associated with.Historical events had a major impact on family migrations.
There are a lot of variables.Genealogical research requires a lot of time and evaluation.It is not a simple dot the "i" and cross the "t" acivity.
Good luck in your research.I have been doing this for the last 23-years.