Think there might have been a bit of licence with Amelia's use of 'widow' in 1851.

1841 Crearton, Merther HO107/148/2 folio 6 pg 6
Richard Bonetto 75 ag lab
Amelia 24
John 5
Harriet 3
Charlotte 13
all born in county
all from opc database
Elizabeth Benetta buried 11/12/1838 aged 47 of Carharthen in Merther
Richard Benetto buried 27/9/1847 aged 85
John Henry Benetta baptised 26/5/1844 in Merther son of Amelia, spinster.
IGI batch C022841 Merther parents Richard & Elizabeth/Betsey Benetta
Amelia born june 1815 bp 6/6/1819
Maria bp 6/6/1819
Jane bp 6/6/1819
Eliza bp 26/5/1822
William George bp 2/5/1824
Grace bp 22/1/1832
John bp 21/9/1834
Harriet bp 13/4/1838
same batch - mother Amelia Benetta
William Henry bp 7/6/1835
Eleanor bp 22/11/1842
Henry Francis bp 10/7/1843 (opc database seems to suggest this is same child as John Henry)
burials on the opc site for Grace in 1838 and William Henry in 1839.
birth reg
Eliza Jane Bonetto june qtr 1850 Truro vol 9 pg 328
Both Eliza Jane and Harriet were baptised as Bonotto 13/2/1862 in Truro, St Clements daughters of Amelia - on opc database, but not on IGI. No sign of a baptism for Elizabeth as yet.