From what I have learned, Amariah Lincoln was the son of Ichabod and Malinda Lincoln. Amariah and Melissa Spencer married about 1848, and had 5 children: Frances, Francis (Frank), Eva, Belle, and Emma. On 1850 census, they lived in Orangeville, and by 1870 were in Sheldon. Appolles Lincoln was an early settler of Orangeville, so possibly he is Ichabod's father.
When did your Lamb's move to MI? Wright Spencer (Melissa's brother) moved to Ingham Co in 1869.