Quirk virtually guarantees you a Manx relation !
Allgood is not a common name on Island but On the 29th May, 1716, Mary Henricks of Douglas was presented by the churchwardens and convicted of adultery with Isaac Allgood so the name is in Manx records (however that is the only ref I have)and I suspect he was a soldier and thus quite possibly from Lancashire as employed by Earl of Derby.
Malvina Christina are both highly Non Manx names!