There is really no way to train them or ask them not to break items. You can ask them to join the household as a ghost if you want to fully control them. They are actually fun to play at times. They do have all the same needs as a living sim, so they will need a bed and they will raid the fridge once in awhile (I make mine live in a basement room). You can direct them to haunt items (which will break plumbing), scare sims etc. On the plus side is they can ghostly repair broken items. They'll zip into the broken item, make it float for a bit, and the item will be repaired when they are done.
On the flip side, just designate a "cemetary"lot (I use the generic lot trait) and plop good old dead hubby's urn there. Have his widow visit on occasion.
