What will happen to the transactions with unconsumed states when modified contract is integrated in the network

Question

I have build a CorDapp using "Yo!CorDapp" example (https://github.com/corda/spring-observable-stream), over release-v1 of Corda platform.

The CorDapp has four nodes - Controller node (provides network map service and validating notary service), "node A", "node B" and "node C". Following are the flows defined in the app -

Flow 1: "Node A" sends a trade request to "Node B". "Node C" is also notified.

Flow 2: "Node B" approves the trade request, self-signs it, gets signature from A and closes the trade. "Node C" is also notified.

Consider a scenario -
-a transaction record is created that is initiated by Node A and is still to be approved by Node B. 
-the contract code is modified to add more checks and is integrated in the corda network

Can Node B approve the transaction after the integration of modified contract?