there are two William humms in great Henny having children at the time.
There is a William humm junior (born 1784). He married an Elizabeth (will have a look for the marriage later). They had the following children: William 26/4/1807, Samuel 6/10/1811, james 21/11/1813, John 26/1/1816, George 6/9/1821
William humm senior (I think born 1763 to John and Elizabeth humm. This William was married to a Rebecca. They had children from 1784 to 1806.
Other humm family names are Sarah, Edward, Elizabeth, james, Susan, David. Do any of those appear in your Frederick's children or grandchildren's names?