This post is to anyone reading this.
If you want to create a custom with a multi-stage program, I would encourage you to consider purchasing the program at the main shop, running each stage as per current recommendations, then putting the stage you want into the custom (I prefer stage 4, because as of now they tend to be comprehensive) when you’re all done going through all the stages.
If you want to make a custom, you could make one to listen to as you listen to your multi-stage one, just perhaps build it without any multi-stage modules (unless you’ve already gone through all stages).