I'm investigating further into my orbital overlap problem. I've already looked into the overlap ($0°$ angle between the two orbits) of two planets in a circular orbit around the sun. I'm now trying to find a method of doing the same for an elliptical orbit. For the circular orbit I used angular velocity as a function of time to calculate the time at which one orbit is exactly $2\pi$ ahead of the other orbit. How can I do this in an ellipse?
The data I have available:
Orbital Periods, Distance at perihelion and aphelion, Velocity at perihelion and aphelion