The Canon eTTL system is entirely different than the Nikon iTTL system, so your 430 will not work in TTL mode with the SB910.
But if the 430 has an optical slave mode, it will work with the 910 in SU-4 mode. Then, the pop-up flash in the D600, in Manual mode, will fire both slaves. Of course, the power setting will be totally manual on both the 430 and the 910.
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