Foreclosures

Supposedly, with the advent of mortgage backed securities, and all the other mortgage instruments, there are many parties owning various pieces of the mortgage. When the mortgage enters default, the explanation is that it is so hard to find/determine who all the owners are, that it is impossible to gather their input to help restructure a mortgage to stave off foreclosure.

So in the event of foreclosure, if it is so hard to determine who the creditors are, how can they get paid in the event of the foreclosure and subsequent sale? In fact, it would be an interesting scenario if there was a legal requirement that each owner of the mortgage had to personally approve a foreclosure and that the administrator of the mortgage could not enforce it by itself.