at that period there was no official adoption requirement - any such would be private family arrangements.

There would be no Manx will for George unless he had Manx property - can't see any such will in index to Manx wills - you need search in English records as there is likely to be at least some administration decree.

At that period master mariners often had their wives on board with them - possibly George, Anne + youngest child all drowned - might well be worthwhile to search Liverpool papers for any report of the founding.