William Sr. & Andrew arrived in Boston aboard the vessel Nanset in Oct 1859. There was no sign of Christina or any other children.
William Jr. died in 1863 in Massachusetts according to record on familysearch.org. I could find no sign of the Morton family after that.
1860 census Malden, Middlesex County, Massachusetts
William Marton 29 b Scotland (calico printer)
Sarah Marton 28 b England
Sarah Marton 4 b England
William Marton 3 b England
Andrew Marton 16 b Scotland (machine tender)
William Marton 62 b Scotland
I sent in a correction to ancestry on the surname.