Your ggparents must have been avid readers - Lemuel from Gullivers travels, Marguerite from Faust and possibly Greeba from either the Manx place or Hall Caine's novels!
Greeba is at http://www.manxnotebook.com/people/writers/thc.htm

the only Christian Crellin in 1881 census for IoM was:
parish of Braddan Virginia House CRELLIN Evan Head Widow M 44 Farm Labourer born Kirk German IoM
Braddan Virginia House CRELLIN Jane Daur U F 21 House Maid (Domestic Serv) K German IoM
Braddan Virginia House CRELLIN Elizabeth Daur U F 18 Dressmaker K German IoM
Braddan Virginia House CRELLIN Eleanor Daur - F 15 General Serv K German IoM
Braddan Virginia House CRELLIN Edward Son - M 13 Farm Servant ((Labourer)) K Braddan IoM
Braddan Virginia House CRELLIN Christian Daur - F 11 Scholar K Braddan IoM
Braddan Virginia House CRELLIN Eliza Daur - F 9 Scholar K Braddan IoM
Braddan Virginia House CRELLIN George Son - M 7 Scholar K Braddan IoM
Braddan Virginia House CRELLIN Joseph Son - M 5 Scholar K Braddan IoM