There is a book on this Gramm family by Ruth Bangar Gramm, Descendents of Henry Gramm in the U. S. A. I know it can be found in the Family History Library of the Church of Jesus Christ of Latter Day Saints.
I have communicated with various cousins on this line and have posted my work on the GenCircles web site.
In brief, Heinrich was married to Christiana Kendig and had two children, Maria and Henry. After Christiana's death, he married Esther Sautter. This marriage resulted in the other five children. I am descended from his son Henry.
I hope you find my information useful. For this generation, you may wish to view the information of Kerry Simi, Todd S. Kendig and Donald Johnson among others.