Here's the missing 1871 census entry. Note that Eleanor is called "Eliza" here:
1871 Census at 4 West View Douglas RG10/5775 109 pg 16 #81 (895844)
Eliza GELLING, Head Wd 54, Income from Int of Money, b Liverpool
Edw GELLING, Son Unm 34 Grocer, b Douglas Isle of Man
Elizth GELLING, Daur 30, b Douglas Isle of Man
Cath GELLING, Visitor Unm 65, b Douglas Isle of Man
Elizth KILLY, Serv Un 32 Domestic Serv, b Douglas Isle of Man
Isabella KILLY, Serv Unm 18 Domestic Serv, b Douglas Isle of Man
I chased down the unmarried 65 year old visitor Cath Gelling, to see if she could be a sister of Edward.
Some census entries of 3 spinster sisters Elizabeth, Jane and Catherine. Typical of spinsters of that day I think, they greatly reduced their ages as time went on.
1841 census at Castle Street, Castletown, Malew HO107/1464/5 3A 52 pg 25 (464356)
Eliz GELLING 45 Silk Merces? Y
Jane GELLING 40 Y
Cath GELLING 35 Y
1851 census at 3 Great Nelson St, Douglas HO107/2525 263 pg 6 #22, Living with large BRIDSON family
Elizabeth GELLING, Lodger Unmarried 60 Annuitant, b Isle of Man Douglas
1851 census at St Mary's Square, Castletown HO107/2526 165 pg 13 #49
Jane GELLING, Head U 49 Annuitant, b Isle of Man Douglas
Cathrine GELLING, Sister U 40 Annuitant, b Isle of Man Douglas
1861 census at Castle Street, Castletown RG9/4414 50 pg 13 #82 (543279)
Jane GELLING, Head Un 50 Annuitant, b Isle of Man Douglas
Catherine GELLING, Sister Un 42 Annuitant, b Isle of Man Douglas
I could be wrong on this, but I think this will be the parents of Edward. Source is IGI, so needs to be checked with registers.
Daniel GELLING m Catharine COTTEEN 16 Feb 1790 Malew. Children bp at St Matthews Douglas:
Elizabeth 4 Sep 1791
Jane 31 Sep 1792 (IGI says Danl GELLING & Cath CALLOW, so might not belong here)
Jane 28 Jul 1793 perhaps the "Jane Gelling child" on the burial index bur 20 May 1794
Jane 30 Jul 1794
Charlotte 15 Sep 1796
Edward 24 Apr 1799
Margaret 18 Apr 1804 bd 22 Nov 1808
Catharine 4 Dec 1804
I don't know who Daniel's parents would be. No sign of Daniel and Catharine on the 1841, so they had probably died by then. He must have been fairly properous to provide support for 3 spinster daughters. The missing person still is Charlotte b 1796.