I don’t have this setup, hadn’t even heard of it, so I looked it up and checked it out.
Looks like the strap connects at a balance point of the system so you can operate it with the neck strap functioning in a “load bearing” capacity. The original attachment points function more as a “security” point where you take the load, what little there is, in your arms. If you let go or slip, it just flops down like a heavy necklace, or you can let it hang intentionally so you have use of your hands.
You could try using the original attachment points with one of the aftermarket solutions that have strap loops or whatever system, instead of the two included. This would enable you to use a neckstrap for security, but the load bearing would be your arms.