Hi,
I have done quite a bit of work on the Gick tree and have information back to about 1620 or so. This includes data that is consistent with your records on Jane Gick and William Kelly, but I do not know about Jane's sister marrying another William Kelly.
If anyone knows about a John Gick who might have lived in Ireland around 1850 I would be very interested to know about him and his links back to the Isle of Man.