Instead of buying C & D, simply download for free. It acts as a mixer and gives you multiple virtual I/Os that work just like VB-Cable.
Virtual audio routing can be tricky, but has simplified the process for years. While the standard VB-CABLE is free (donationware), the C and D packages are additional drivers for users who The Deal with VB-CABLE C + D vb-cable c d free download
However, a workaround if you need more than 1 virtual cable for free: Instead of buying C & D, simply download for free