From the EstateState.blogspot.com
Robert Todd Lincoln Beckwith was President Lincoln's great-grandson and was thought to be the last Lincoln heir when he died in 1985.
Some people think that a Lincoln heir survives.
Robert Todd Lincoln Beckwith was married three times and claimed that he had no heirs. His second wife claimed otherwise. His third wife found out she was pregnant six months after the wedding, but Beckwith had had a vesectomy.
They divorced in 1976 where a trial was set in motion to determine whther the boy Timothy Lincoln Beckwith was a leigtimate Lincoln heir. He was seven at the time and stood to inherit more than $10,000,000. The boys mother left for Europe and refused to return. The divorce was granted and the court ruled that the child was the product of an "adulterous relationship." The judge said that another court would have to rule whether young Timothy could still seek the Lincoln fortune.
When Beckwith died in 1985, the three groups that were to inherit his millions -- Iowa Wesleyan College, the American Red Cross and the First Church of Christ, Scientist -- were worried about Timothy Beckwith, then 17 years old. The groups made him an offer -- the teenager said yes, and with that the "Lincoln family tree withered into history."
Wickipedia article here
Lincoln Family Tree Here,
It is possible that Dakota had a vasectomy too which is not uncommon among young males joining the military. Even though young Timothy was not an heir to Lincoln he still cashed in anyway. Not to give Bristol any ideas but that might be her plan.