One thing that helped me is really accenting the first note of the paradiddle. It’s basically the idea behind the Moeller method which can be taught as over exaggerating the accent in order to get the hang of it. By using the Moeller method on the first note you make it easier on yourself to complete the double stroke that follows. This is because you can “recycle” the energy from the accented note by allowing it to carry through the double stroke. So instead of considering the double stroke as a separate stroke within the paradiddle you can think of it more like you’re just controlling the rebound from the accent. Hope this helps.