1813 Abraham Sperling Will

In a post labeled John Michael Sparling in NJ, I provided a list of occurrences of this name and its variations.  The last item on the list was as follows:

1813. John Michael Sperling serves as a witness to the will of Abraham Sperling. John Gilliland Sperling is Abraham's son mentioned in the will. Location: North Brunswick, Middlesex, NJ

Very recently, I have been convinced that there were three generations of John (Jan, Johannes) Michael (Michiel, Magiel) Sparling (Sperling).  Take your pick of spellings.  The first one, Jan Michiel Sperlingh, was an immigrant from Saxony (Germany).  He was a clerk and often called upon to witness legal papers.  He had a son, John, who I believe was also Jan Michiel, who also had a son, Jan Michiel, in various spellings.

The issue with the 1813 will is to determine which of these Johns was witness to Abraham Sperling's will and to identify each of the individuals mentioned.  I think, using age as a criterion, that we can eliminate the first two generations, Jan M., born no later than 1690-ish (?), and Jan M., born no later than 1730-ish (?).  The most likely candidate is Jan M., born 1756, and Abraham's brother.  

I identify the brother, Abraham, by the mention of his son, John Gilliland Sperling.  This confirms him as the Abraham Sperling, b. 1759 at Six Mile Run, son of John Sperling and Catherine, who married Leah Gilliland (1781-1835).

1. Jan Michiel Sperlingh (immigrant from Germany) m. Geertje Pieters

+2.  Jan Michiel Sperling (John) m. 2nd wife Catherine

++3. Jan Michiel Sperling (Johannis Magiel) b.1756, Six Mile Run, NJ

++3. Abraham Sperling b.1759, Six Mile Run, NJ, d. 1815, m. Leah Gilliland (1781-1835)

+++4. John Gilliland Sperling b. 1800

I believe this is how the generations look when stripped to the essentials and that the last three names on this list are the names on the 1813 reference (above) to Abraham's will.