I wonder does the following fit in with your family at all? It seems with the mention of a Prosper Le Feuvre and his daughter Mary marrying a John Loftus must be more than a coincidence?
I did some 'googling' and found that there is reference to a Eugenie Marie Henrietta Le Feuvre being the wife of John Loftus. These could well be the same people with their names slightly 'altered' between France and the Channel Islands.
1851 Census Gresley Cottage, Trinity Jersey
Prosper A Le Feuvre (49) B 1802 Ag Labourer B France
Jane Le Feuvre (50) B 1801 Wife France
Mary Le Feuvre (14) B 1837 Daughter B France
By 1861 Mary is Mrs John Loftus living in St Helier Jersey (Loftis is spelled Lofties on the 1861 Census)
1861 Census at 11 Dorey Cottages, New Road, St Helier Jersey
John Loftus (23) B 1838 Brickmaker B St Helier Jersey
Mary Loftus (24) B 1837 Wife B Trinity Jersey (This Census states Jersey birth, others France)
Mary J Loftus (2) B 1859 Daughter B St Saviour Jersey
Alice M Loftus (1mth) B 1861 Daughter B St Helier Jersey
1871 Census at Ronde Porte Cottage, St Saviour, Jesey
John Loftus (33) B 1838 Brickmaker B St Helier Jersey
Mary Loftus (35) B 1836 Wife B France
Mary J Loftus (12) B 1859 Daughter B St Saviour Jersey
Alice M Loftus (10) B 1861 Daughter B St Helier Jersey
Susanna Loftus (
B 1863 Daughter B St Saviour Jersey
John Loftus (4) B 1867 Son B St Saviour Jersey
At the time of the 1851 Census, John Loftus is a Lodger in Jersey at 5 Simon Place, St Helier residing in the home of Isaac Cradick from England, he is described as 'Nephew'.
Loftus is transcribed as Loftes on the 1851 Census
John's occupation is stated as Brickmaker and his place of birth as England. All later Censuses state that he is born St Helier Jersey, but having lived in St Helier a long time, this could explain why it was cited as his place of birth.
From my google search it appears that John and Mary Loftus and their children immigrated in 1873 to Rockhampton Queensland Australia.
In 1881, there is a Prosper A A Le Feuvre in St Helier Jersey, this could well be the brother of Mary (Eugenie?)
1881 Census at 4 Eden Place, St Helier Jersey (transcribed as Le Feuver)
Prosper A A Le Feuvre (46) B 1835 Vinegar Distiller B France
Susanna Le Feuvre (44) B 1837 Wife B England
Francis J Le Feuvre (14) B 1867 Son Errand Boy B St Saviour Jersey
Elizabeth J Le Feuvre (13) B 1868 Daughter B St Saviour Jersey
Charles C Le Feuvre (12) B 1869 Son B St Saviour Jersey
John E Le Feuvre (7) B 1874 Son B St Helier Jersey
Youngest Son John Le Feuvre was baptised in St Helier Jersey on 15/3/1874 as John Ernest Le Fevre, son of Prosper Aimable Alexandre Le Fevre and his wife Susanna Le Fevre (nee Pitman). Godparents were Prosper A A Le Fevre and John Moyse
*The surname was clearly spelt Le Fevre on this baptismal record which can be found on the website
http://www.guernsey.society.org.uk/donkipediaAt the time of the 1851 Census, Prosper Le Fevre was a Servant for a John Pallot in Trinity Jersey. His name was given as Aimable Le Feuvre Born 1835 France, occupation Farm Servant, but I am fairly sure this is the same chap.
1861 Census and Prosper was still going by his middle name of Aimable. He was living in Grouville Jersey as a boarder with the Du Heaume family. His name on the Census is given as Aimable Le Pore, but when I looked at the original transcription it is in fact Aimable Le Fevre. An Ag Servant, single aged 26 and born "Department of La Manche France"
1871 Census and Prosper is still going by his middle name of Aimable. He was living in St Martin Jersey. His surname is given as Le Feuvre this time. He is living alone, stated as being married and an Ag Labourer born in France.
His wife Susanna Le Feuvre was residing in St Saviour Jersey with John Phillips and his family. She had with her their children Francis J, Elizabeth J, Charles C and Ernest W, the latter who was born 1871.
Ernest is not mentioned on the 1881 Census, so I'm assuming he died between 1871 and 1881
1891 Census at 2 Ann Street, St Helier, Jersey
Prosper A Le Fevre (56) B 1835 Vinegar Manufacturer B Besnemble (?) France
Susanna Le Fevre (54) B 1837 Wife B Christchurch Hampshire
Charles C Le Fevre (21) B 1870 Son, Blacksmiths Fitter B St Saviour Jersey
John E Le Fevre (17) B 1874 Son, Blacksmith's Apprentice B St Helier Jersey
Elizabeth J Le Fevre (23) B 1868, Daughter, Single, Laundress B St Saviour Jersey
On the 1901 Census Prosper and Susanna are living in Southampton Hampshire, the name on the Census is showing as "Le Ferre", but I am sure is Le Fevre on the original transcription. Living with them are son John, daughter in law Isobel and Granddaughter Mabel.
Hope it is of help to you.