you could apply for a certified copy of the marriage entry from the IoM Gen Registry (see family history under manxnotebook (on tabline) - as civil reg was late on Island the Parish regs were copied in 1911 and these copies are those used by gen registry and also the basis of the Mormon IGI - however the IGI has many errors in transcription (silk purse to sow's ear is my usual description) - some of the 'patron submitted' are actually batch corrections of some parishes - if you borrow the original film of the 1911 transcription (see film nos on manxnotebook) then you will get any additional comments + witnesses (comments might just give county in Ireland).
By 1841 Isabella was apparently a widow living with dau ann who had married miller Robert Waterson (Mill easment near carmodyl beg in Ballaugh) - another daughter Matilda was a servant in German parish - however I don't see a burial for Daniel in Brian's index (www.lawsons.ca)