What if... Jacob caused Rachel's cancer so that the she had to have chemotherapy and her reproductive system to be messed up. The Juliet would try to fix her. she was fixed but not by Juliet but rather by Jacob. as a result of her being fixed Mittelos Bioscience would then be sent by Jacob to get Juliet . Juliet would then think that she really is "that good" and accept to go to the island even though she is not responsible for the fixing of Rachel. then when Rachel supposedly get cancer again, Jacob gives it to her and makes Juliet stay on the island because he would fix Rachel. All this was done by Jacob not because Juliet could solve the fertility problem but because she is a candidate (or at least was at the time).
I think that the same thing happened to Dogen. Jacob somehow caused the accident and told Dogen that his kid will live if Dogen came to the island. Dogen, like Juliet, could not say no so they agreed. Jacob also wanted Dogen because he was a candidate too.
Jacob would do anything to get his candidates to the island and keep them there until they either die (not the right candidate) or become the new protector. Sometimes you could just Guide someone to the island by touching them, other times you just have to convince them by giving them a choice knowing already what they would chose.