It is an expected behavior to be able to split a workflow into two routes using Post Functions.
Using Post Functions, OR Validators, I can't seem to get our workflow to split. https://answers.atlassian.com/questions/143150/skip-or-follow-a-transition-step-based-on-cutom-field-value goes over this, and I have looked into a number of other answers that essentially say the same thing. I used the following:
Adding scripted function
Adding a mirrored step
Adding a mirrored step with a validator
Attached are screenshots and the workflow in XML and WF formats.
Further complicating matters, we have to sync these with Parent issues, but I think I can figure that part out.