Q. Can I set a specific NIC to be used for Hyper-V Replica traffic?
A. No. There is no configuration to specify the adapter/IP to use for Hyper-V Replica traffic. Hyper-V Replica will use whatever paths exist between the source and the destination. Even if you add a specific path if other paths also exist they may also be used since SMB is used for Hyper-V Replica and SMB supports SMB Multichannel which can use multiple paths concurrently to transfer traffic.
If you search the Internet there are posts that utilize the Hosts file to block certain routes however this is not recommended as Hosts files quickly become very hard to manage and can cause more harm than good.