Welcome to the black hole of Wonderlin/Wonderlan/Wonderland research in New Jersey. My GG grandfather was James Wonderland who was born about 1816 in Burlington County. In 1840 James was married to his first wife and living in Tyrone Township, Huntingdon County, Pennsylvania.
The 1830 census contains three Wonderl*** names in New Jersey.
The first is John Wonderlin, age 70 to 80, in New Hanover Township. This is the John Wonderlin you found in New Hanover in the 1840 census, age 80 to 90. I have a copy of his will which names two children, an adopted daughter Hope Johnson and a son Peter.
The second is James Wonderlin, age 30 to 40, in Chesterfield Township. He had two sons, one age 10 to 15 and one age 15 to 20. Assuming the ages you had for John and Andrew are correct, one of them could be the younger son.
The third is Peter Wonderland, age 40 to 50, son of John in New Hanover, who married Hester Anderson in 1811 in Burlington County. In 1830 Peter was living in Waterford township and had two sons, one 10 to 15 and one 15 to 20.
The John Wonderland you found in the 1840 census in Waterford Township was 60 to 70. Based purely on the ages in the record he appears to have a married son age 20 to 30 and a grandson under 5. This son may be the John Wonderlin, age 37, married to Susan and living in Evesham Township in the 1850 census.
Two other marriages
John Wonderlin married Phebe Doughty on 4 February 1822 in Burlington County. This could have been a second marriage for either John in New Hanover Township or John in Waterford Township in 1840.
Aron (Aaron) Wonderlin married Hannah Rockhill on 5 August 1809 in Burlington County. Aaron served in the war of 1812 and moved West.
I have been collecting anything and everything I could find on Wonderlands in all itâ€™s various spelling in New Jersey. It seems they should all be related somehow but I have not been able to find the connections. If you find something that makes these connection please let me know.