I got Jacob Swartz' will transcribed and was a bit surprised by what it contains. It definitely narrows down his death date and separates his children into first wife and second wife.
In a nutshell, here is what it says:
10 April 1852 - original will made. Gives $5 each to sons Frank, Anthony and Joseph. Leaves all land, stock and personal goods to wife Gertrude. Sons Nicholas, John and Peter to divide said property after her death.
14 May 1854 - codicil made. Adds son Mathias to share in property.
This serves to narrow the date of his death to between 14 May 1854 (date of the codicil) and 22 March 1855 (date the will was filed for probate).
So - it looks like I've got him pretty well tied down. Will check some more land records tomorrow.
Now to try and find out something more on Gertrude in Lake Co., MI.