[Calvin Locke]

Just guessing, but wouldn't the dwarf have a mass "nearly" the equal to the red giant? I would think
that the center of mass of both stars would be outside the red giant's outer layer.

Unless the orbital speed is really fast.

[King Prout]

also just guessing, but I think the white dwarf will have lost mass during its collapse phase.

as to where the centermass would be, a crude illo:

satellite>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>CM>>primary
o>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>+>>>>>O

RGcirc>>>>>>>>>>>>>>>CM>>>>>>>WD>>RGcirc
(>>>>>>>>>>>>>>>>>>>>>+>>>>>>>>>o>>>>)