That Mercan lawyer FUD just won’t die - they reported one anecdote about Austria refusing a student permit to a child of a Portugal ARI family, and warn about “EU law” which prohibits multiple temporary permits 
This has been discussed earlier.
I have an equal and opposite anecdote: kid with a dependent GV permit got a student permit from the Netherlands. The Dutch university admission form specifically asked, “OK you’re a third country non-EU national, do you by any chance have a permit from an EU country? You do? Great, upload a copy here. You won’t need an MVV visa to enter the Netherlands, just get in here and make an appointment with the IND for your student permit” and the IND office in Amsterdam asked for passport, existing permit, university admission and issued a student permit after a few weeks.
I have first-hand knowledge of two cases of students from two different PT ARI families belonging to two different countries getting NL student permits. Similar procedures apply for work permits in the Netherlands as well, though I have no first-hand knowledge.
Some EU countries may have problematic rules, but I am convinced that there is no overarching EU rule which disallows this, and no one has ever cited an authoritative source for such a rule.