Hi and thanks for your question.
First off, I'm going to describe the situation we're handling, because I think I understand it now:
Your iPad is connected to the MIDI Target. Your iPhone is only connected to the iPad and not to the MIDI target. If this is wrong, stop reading and leaving a comment ;)
In this case, you would NOT be touching the actual program change button, ever. You would make a supercontrol of the program change button and touch that (on the iPad). Let me know if you need specific instructions on how to set up supercontrols. Set up a control with the same Channel-CC as the supercontrol on your iPhone. Now when you touch your iPhone, the supercontrol on the iPad will cause the subcontrol to send out the Prog change.
Let me know if you have questions about how to set any of this up.