Weird. They (Neera, Aerie and Imoen) could cast the special abilities they learned after lvl 20 or so (summon planetar, energy blades, greater alacricity etc) but whenever I had them right-click a scroll, there was no option to "write magic" for any lvl 9 spell (wish, time stop and Imprisonment, if I recall correctly).
I did have the enhanced edition, though.