Hi Donna & David,
Donna, what you have written from the 1851 census looks like the family of Thomas Christian & Margaret Moore who married in Maughold 29 Jun 1816, with consent of parents.
1841 census, 1 12 51 Port-e-Vullen Village
Thomas CHRISTIAN 40 Linen & Woollen Weaver Isle of Man
Margaret CHRISTIAN 40 Isle of Man
Thomas CHRISTIAN 15 Isle of Man
Robert CHRISTIAN 10 Isle of Man
Elinor CHRISTIAN 7 Isle of Man
Children bapt Maughold:
Catharine [daur of] Thomas Christian/ Margaret Moore [bapt] Parish Church 18 Aug 1816. Twin of Margaret
Margaret Thomas Christian/ Margaret Moore Parish Church 18 Aug 1816. Twin of Catharine
Ann Thomas Christian/ Margaret Moore Parish Church 9 Jan 1820
Thomas Thomas Christian/ Margaret Moore Parish Church 16 Mar 1823
Robert Thomas Christian/ Margaret Moore Parish Church 3 Sep 1826
Elinor Thomas Christian/___ Moore Parish Church 13 May 1832
William Thomas Christian/ Margaret Moore Parish Church 1 Nov 1835
1861 census, 1 99 Port E Vullin
Thomas CHRISTIAN Head WID 65 Weaver Maughold
Ann CHRISTIAN Daughter UNM 42 Maughold
Ellen SAYLE Daughter MAR 28 Maughold
Robert KNEEN Grandson UNM 14 Scholar Maughold
William CORKILL Grandson 10 Scholar Maughold
So Margaret died between the 1851 & 1861 censuses.
Margt. CHRISTIAN 64, Port y Vullin, buried Maughold 16 Apr 1860
Their ages are pretty consistent, and this is probably her baptism:
Margaret daur of Robert Moore & Margaret Cannon bapt Maughold 3 Apr 1796.
Thomas CHRISTIAN 70, Port y Vullin, buried Maughold May 14 1865.
Probably Thomas son of William Christian & Ann Kelly bapt Maughold 7 Feb 1796 (who married in Maughold 10 Jun 1783 - Ann from Bride).
So both Thomas & Margaret underage at their marriage, hence the parents' consent.
David, are you certain it was the Port-e-Vullen Robert who married "Catherine (surname unknown) who was born Arbory"? Where did you see this record? Robert's age as 22 looks wrong in the 1851 census - see bapt 1826 above - but I can't see another family who fits the names given in the three censuses. There were other Robert Christians b.1826-1830 married to other people. There was one Robert b.1826 Maughold married to Agnes, but no marriages found after 1850 in Maughold for Robert with father Thomas. (Several Robert Christians with other-forename fathers.)
Sue