FINALLY GOT OUT THIS YEAR
. And my nephew had a break through which may help you.
Tighten your stance i.e. Boot touches boot tight (No flames please....) and do your turns (and try to keep them together). Don't worry your stance will be ok, it is just to get rid of A frame which likely feels like a weaker foot. This is a confidence thing (one photo looked odd, and I think this is the cause as in the turn your foot looks like it slight behind and it should be ahead, this is something that you typically see in A Framing).
What finally did it was 5 runs on SL's (last run sort of clicked after I threatened him to tape his boots together), Lunch (1 hr), switched to GS and WOW different amazing skier. And he just get better from there. The above I've been trying to get him to do for about 3 years (he's only18) and finally
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Cheers,
G
added details as iphone is a pain to type on.