Any possibllity of getting an aircraft code that could be used for the A320 family? Unfortunately, A32* can’t be used to get all of the A320 types flying because of the A319 and A318. (Have to use A31* for those two aircraft.)
Is the A318 considered to be part of the A320 family?
[sarcastic mode on]
Well it isn’t part of the A300/310/330/340/380 families, so I reckon so! 
[/mode]
Yes, the A318 is part of the A320 family. It has the same fuselage (shorter, of course) and engines, with a range similar to that of the A319. Interestingly, it’s tail is taller than both the A320 & A319, maybe to give the “shorty” a little more stability in flight? Not too many sold, though. Somewhere in the 30s or 40s, I think. Frontier is the only American carrier w/ them, AFAIK. A’s website has all the info, including the family groupings.