Welcome here @trinicloud
There’s regular beta releases of O3, the best that can be done at this point is to rely on the latest beta at a given time. At the time of this writing that’s 3.0.0-beta.13.
You’re saying that a third party system will register patients and books appointments. That’s a pretty standard thing to do with an EMR. It’s been done in various ways with OpenMRS by various groups to address various use cases
It is a lot more of a WordPress question than an OpenMRS question tbh.
Perhaps see this thread → List of certified implementers ?