NRM creation

Hi,
If I need to create a NRM for an object then below which one is a better approach :-
Points to be considered is ,The object has 3 different lists which has 3 different keys for each.

  1. Creating a single Model with all the 3 lists in one config block .(but how?)
  2. Creating 3 different Model which can create 3 different NRM for each list and key.

Thanks,
Nitesh