So here is the all new confirmed descendant chart:
William_McRobie_Confirmed_Descendants.rtf
For those of you with genealogy software I have even created a gedcom file:
William_McRobie_Descendants.ged

This lists only those who I have confirmed via censuses and other reliable sources up until 1860. Some notes on them:

Sarah McRobie (daughter of John William & [Unknown])–thanks to an exchange with Marylynn Glover, I have confirmed that John William was indeed married twice before Delilah Murphy. Sarah is a daughter by his second wife that was born between John (1824) and Hugh (1828). She does not appear on the 1850 census with her family. She is said to have died young, as does Hugh. Hugh, however, does appear on the 1850 census at the age of 22.

So the chart has been altered as follows:
John & First Wife – Andrew
John & Second Wife – John, Sarah, Hugh, Melinda
John & Delilah – Eleanora, Abraham, Elizabeth, Francis, Hester, Thomas

I have left Joseph off of this version of the chart until I can confirm his parents. I still am of the belief that he was not a biological son, but I can always be wrong.

As for Elisha Dewitt’s Line I have had to make some assumptions. The first being the real parents of Elisha McRobie [b. 1854]. He first appears on the 1860 census in a very broad household. Elisha Dewitt is listed as the head of household, married to Azenath. Michael is living at his father’s house with his wife Elizabeth, and their daughter Nancy. Susan has returned home [presumably widowed] and three younger children are listed with her: John (7), Elisha (6), Elizabeth (5). Even though most of the unsourced family trees I have seen attribute Elisha to Elisha Dewitt, I think it is just as possible that he is really Susan’s son from her first husband. To be fair it’s not outside the realm of possibility that all three (John, Elisha, and Elizabeth) are all Elisha Dewitt’s and Azenath’s children. This is definitely something that will need to be researched much further.

Also William P’s first wife, Lucinda, seems to have died between 1850 and 1860. In 1860 he is married to Sarah. I’m going to guess that from the gap in age between Mary (b. 1855) and Howard (b. 1859) that Lucinda died after Mary and William remarried Sarah. I have yet to find any records to back this up.