Mary Todd Lincoln's family were slave owners, Her sister married Confederate General Benjamin Hardin Helms, who Lincoln claimed was his favoite brother-in-law, and who Lincoln offered a colonelcy in the Union Army, which Benjamin Helms refused and joined the Confederate Army with the same rank.

In any case Mary recieved the services of her fathers slaves, which by law became the property of ol Abraham. The slaves were left with the Todd family when Abraham went to Washington because Wasington D.C. had passed a law in 1850 that freed any slave foreign or domestic within the city limits of Washington D.C. including the servant of foreign diplomates. These slaves were purchased by the United States Government for $100 apiece and shipped to Liberia. This is why Mary (an Abraham) didn't take her servants to Washington. Mr. Todd would hve lost them.

This would also seem to explain why slave owners in Kentucky who could prove they were loyal to the Union did not have to surrender their slaves until December 1865 when the 13th amendment was finally ratified. Those slave owners who could not prove their loyalities to the Union had their slaves declared as contriband and confisated.

Certainly the Father-in-law of the Presdient of the United States had no problems in proving his loyalities.