I don’t know why I didn’t realize this after Daniel “left”. When Jack, Sun and co. were down in the Lamp-Post with Ms. Hawking she said a strange little line, she said, “a very clever fellow built this pendulum on the theoretical notion that they should stop looking for where the island was supposed to be and start looking for where it was going to be”. It seems very likely that Daniel, as a Dharma scientist would build something like the pendulum. And it explains why Daniel’s mom would call the man a “very clever fellow”.
I also believe that Daniel some how communicated with his mother in the future, or at least sent her messages, that would explain why she’s so dismissive of Desmond’s message for her.
I don’t understand why Dharma would need to locate the island in 1974. They must have known where it was by that point. (I may have just disproved my own theory.) No, I think it’s still possible and likely.