Banjo and Kazooie are first introduced to Soggy in Freezeezy Peak, Soggy is very upset because she doesn't have a present for Christmas. The duo search the winter wonderland and find three presents, one for Soggy and the other two for her siblings Groggy and Moggy. After you give Soggy her present she celebrates by jumping up and down, if you complete the quests involving Boggy he is sat in his chair trying to sleep and annoyed at the children's happiness.
Banjo and Kazooie meet Soggy again in Witchyworld, the pair meet Mrs. Boggy at the entrance, she wants the bear and bird to locate her three children. Each child is not happy about leaving and has there own requirements to get them to leave, Soggy's requirement is that she wants you to get her Fries. Once you return all three children to Mrs. Boggy she will give you a Jiggy and leave Witchyworld with her children.
You see her again in Hailfire Peaks, she is on the ice side in the family igloo. She is downstairs in the children's bedroom, if you talk to her she said she hopes Moggy gets in trouble for jumping on her mothers bed. This gives us a slight indication that she is a tell tale and enjoys watching her sibling get told off.
Soggy and her siblings were supposed to be in this game, some of the promotional art shows Soggy. They were cut from the game due to time constraints, they were to be in a mission called "Don't bring your kids to work day".