that favours one or other of the waves will result in higher received
power. This indicates that both waves are independent and available to
the receiving antenna, the waves do not cancel in space, but rather the
superposition occurs in the antenna.

It's really very simple:

at each point in free space at a specific time t, there is only ONE
value of the (vector) electric and magnetic fields,

E=(E_x(x,y,z,t),E_y(x,y,z,t),E_z(x,y,z,t))
B=(B_x(x,y,z,t),B_y(x,y,z,t),B_z(x,y,z,t))

to find those values, you simply add up what comes from various sources
of the fields. Separate antennas do not have their "own" E and B that
is independent.

Tor
N4OGW