Given one image point in the angle domain,
and the four angles defining the two plane-waves
(two azimuths and two dips),
the two plane-waves are positioned such that the image point is
contained in both.
The directions of the two plane-waves provide the azimuth and the
dip of the reflector.
The image point is contained in the intersection of the two plane
waves.
To find the plane of the reflection we define the apparent
propagation plane as
being orthogonal to the two plane-waves and passing through the
image point.
Once this plane defined,
knowledge of the rays location and coplanarity is inconsequential.