The only way to find the first Killips to emigrate to the US is to research Killip families in the US, checking out census records etc. Which families went off-island and when will not be recorded in official island records. If they emigrated during the last, say, 150 years this may not be too difficult a task - you may well find a census record stating that someone was born on the Isle of Man. Or they may be traced further back in the US (through land records etc). In any event when you have found that adventurous ancestor who left his Manx homeland, post another message on this board and with any luck someone may contact you and call you cousin.