Silver is immersion plating on unwanted area of nickel surface

Q. Dear all,

I am a plating engineer in a connector manufacturer. The substrate of the connector is copper alloy. One end of connector is silver on copper, the other end is Tin lead on nickel and copper, while the middle part is just nickel on copper. The process flow is : overall copper plate, selective nickel, selective silver strike and silver plate, selective tin-lead plate, anti-tarnish. We found silver immersion on the nickel surface after silver plate. The immersion silver layer is stick on the unloading rollers surface. Can I add a pre-dip before silver strike to protect the nickel surface from silver immersion? Or can I add some anti-immersion agent directly to silver bath to solve this problem?

Thanks!

Lee