Sir Osis of Liver said:I got to go with the majority here, it shouldn't be up to the players to emulate a well rounded four persons party. It's up tp the DM to provide an adventure suitable to what ever they end up making.
I'll pipe up in agreement with this. It's simply impossible for two PCs to mimic the abilities of 4 PCs of the same level and wealth. DOn't ask them to try. Let them make what they want, and design your adventures to tell a story with who they want to be, rather than try to make these two fit into stories suited for a group they cannot be.