ST60 depth trouble

[SaltyGirl]

On the Seatalk-Seatalkng Converter box, how should the 2 white Seatalkng spur connections be used? The yellow SeaTalk spur connection currently goes to a 3-junction SeaTalk hub for my ST60s, but the 2 white SeaTalkng connections are not used.
Based on your response, I need to add a T-piece & SeaTalkng Backbone cable, and connect the itc5 to a spur off the T-piece.The Seatalk-SeaTalkng Converter box is currently at the end of the backbone (with terminator plug), and I can just put the new section in the backbone before or after the converter (moving the terminator plug if I put the itc5 at the end. Is that correct?