I am currently learning to work with solidworks electrical for use in designing a wiring harness for an FSAE car. I have the basics down but I am trying to do some things that I don't believe SWE directly supports such as wires bundled in a concentric twist and covered with heat shrink. I have tried numerous options in SWE but have so far been unsuccessful. At the moment I am reverse engineering a small harness I made earlier this year. As pictured below there are three connectors, from the cylindrical (cube in 3D) connector the wires should be exiting bundled together and at about halfway to the other two connectors this bundle should split into two separate branches leading to their respective connector. I would like to know how I can bundle these wires to show this? I understand I can make a custom cable but this doesn't seem very efficient. In order to make this easier to answer I will break it down to several items, if anyone can help me with any of these it is much appreciated!

1. Line Diagram and cable association: For this three connector harness I have wires running from one connector to two separate connectors, to show that they are bundled together up to the midway point and then split, I drew the diagram as is below. Unfortunately as I do this connector C2 is not recognized as actually linked to either of the connectors. I have however seen this done in tutorial videos and am wondering why it is not recognized in my case.

2. Individual wires or custom cable?: To create the physical harness I decided to go with individual wires at first assuming that there would be an option to bundle the wires together (as if they were covered with heat shrink) Unfortunately I haven't been able to find a solution to this. If this option does exist, how do I go about doing so? I understand I can create a custom cable but this does not seem to be a very efficient method and also causes some issues in not being representative of what I want. Below is the current 3D model and the actual harness.

3. Concentric Twist: Lastly I would like to know if anyone has ever experimented with concentric twists of their wire bundles in SWE, this is not 100% necessary but would improve the accuracy of the dimensions of the harness. Below is a picture for clarification.

Thanks for any help in advance!