Now refer to mass distribution of outer planets in solar system, and you will find that Neptune is rather large; and rather more dense than Uranus futher inward in the disc.

Reason is a collision frenzy between inner Kuiper belt and Neptine with neptune growing to giant planet size as a result. Slingshot events around Neptune have cleared innar Kuiper belt and no doubt a number of inter comet collisions took place (last great bombardment timespan).
Note also pluto is the result of a collision and merger of 2 initial comet. Result is Pluto, Charon 2 named outer satellites and 2 unnnamed more distant satellites formed from the debris disc resulting from the collision.

The fact that CO is being releases indicates that the insolation rate at distance in the discs of the 2 stars indicates that a giant planet is forming in the inner kuiper belt at a distabnce hot enough to release gas from comet collisions. Pluto probably formed in a similar situation but in those days the sun was also cooler and it is likely little CO was realeased @ that time other than in the heat of the impact itself.

Look in IR and the giant planet may be found in both cases in these stars in circular orbit.

Have a nice day: Ag