There is a James Hartman age 40-50 on page 367 of the Chesterfield Twp, Burlington Co 1840 census. Andrew Nelson & family are on page 361.
Since Aaron was born in 1834, according to the 1850 census, and in 1840 there was a boy in Andrew & Salina's household age 5-10, he was born before the marriage of Andrew and Salina.
In 1898 Leonard McClure's widow Alzira applied for a Federal soldier's widow's pension. In her application she states that her husband was previously married, to Lene Nelson. The file includes an affidavit from the NJ Bureau of Vital Statistics, dated April 9, 1898, stating that a search was made for the death certificate for June 6, 1868 and all dates between May 1, 1867 and May 1 1870, of Lena McClure and none was found. (Small wonder, since her death certificate calls her Salina Nelson)
The file includes a joint statement by Mary J Biddle and Alice H Waln, who state that they attended the funeral of Lena Nelson in Mercer Co NJ, on June 9, 1868, and that the funeral director was Esac Middleton who is now deceased. Interesting that they call her Lena Nelson, even though at the time of her death she was Salina McClure. The actual death certificate is in the name Salina Nelson, and states the death date as June 7, 1869. It was not submitted for recording until 3 Sept 1869. There is no evidence of who submitted the death information: doctor or undertaker.