I used to wet my hair first and add Kemi Oyl and braid it up when I swam competitively and practiced three days a week. If she's going to be swimming less than three days a week I would use conditioner. If your hair is dry the chlorinated water goes right to the hair shaft and the more times she swims a week the drier her hair my get. At least if your hair is wet and sealed with oil there's less of a chance of absorption. I would definitely wash her hair after every lesson and let the water run on her hair for a bit before you start to shampoo to remove as much of the chlorine as possible and condition her hair well. I still swim once a week and I just add conditioner to my hair before I put my cap on.
HTH