Question. I have a humminbird 858 on bow and a 998 SI at consol. Both with independent transducers and are both linked up together to share waypoints. I'm wanting to add a Helix 12 to consol, sharing the 998 SI transducer. Is this possible to have all 3 units sharing waypoints, but with the 2 units at consol sharing transducer and what special equipment will be needed?