Sekuneis a great addition to your group! I love this girl cause she is 2nd in your group after your grandfather goes, and then you she is great with a bow and arrow but she needs a shield and and a sword!

Vivenne is strong and is very good for magic perpouses and fighting!
You can get her kinda early or late after you obtain Sekune, and finish Rain you go back to David's house! and go right after you cross the brigde and killing a few monsters make sure you have a lot of healing items cuz you will need them!