I don't have membership records for post 1905 - you are correct in that many sons followed their fathers into membership - to be honest I didn't find any corruption merely total incompetence at administration in the period I looked at. However there were advantages in membership in that you knew many people who could help your advancement or help in trade - pre 1900 I would say most Masons were non-manx born , after this period the advantages for those in the drinks and tourist trade and especially the legal 'profession' became overwhelming, later on it appears the police force were also attracted which did give rise IMO to true worries about impartiality in the justice system. The masons are now much more open re membership but a fully public membership list should help allay fears. I can't help your for your relatives but I suggest you try the archivist at woodbourne rd