Good luck on the Visa's if she has had two before I am sure that will help but they may be a bit more strict as you are travelling with your child.
My partner has a Korean passport but because of the lack of recognition of her divorce cannot get a Philippine passport, now isn't that wonderful she would be a prisoner in the Phils if it were not for her Korean passport.
Anyway it means she does not need a visa to come to the UK but I always have to prepare a letter of support for her and I have always travelled with her when she has come to Britain, they would probably still refuse a penniless Korean citizen if she didn't have a good explanation of why she was coming here.
I have worried about what questions I would be asked if I tried to bring Ana and Janna in at the same time, my daughter has not been here yet, it occurs to me that they might wonder about us arriving as a family, particularly when Janna has the right to stay here and Ana does not, and be more inclined to get awkward at immigration, I don't know maybe I am worrying too much, we would not want to leave me son behind anyway so I doubt she will be back over here for a couple of years yet.