I finally finished this quest after having it flagged for years and am very happy.
But I also have a question. The final CS for the quest has Blandine and Celestina not giving up on finding their Husband/Father. It looks like the quest may have a continuation.
I know that the Sand Charm is a pre-requisite for a couple of quests involving Oswald in Selbina, and also the Pirate chart quests.
I am reminded of a NPC in Norg (around the top of the stairs that leads to Giglamesh's office) that keeps saying that he was rescued by pirates, but he doesn't remember anything. Could he be connected to the people in Mhaura?