the dead are probably the easiest to find + death certs will give addresses etc - once you have identified these then reports of the funeral will often give family members but you are then traceing electoral rolls, telephone directories (little use for most until 1960's) etc all of which require personal search at Manx Museum. If you have several names from the 1920's then an advert in local paper or journal of IoM Fam Hist Soc might help.