Assuming you are using consensus between "miners" (in MultiChain's API) that are preapproved, then there is no need for proof-of-work as a way to prevent someone taking control of the network. We can define consensus in terms of signatures on blocks from these preapproved parties. For more please see page 7 of the white paper:
https://www.multichain.com/white-paper/
(A lot of other things in the white paper are out of date.)
