Clearing CGridView filters and sort orders from the web pages, is usefull for the end user. Yii does not seem to propose a standard method. Furthermore, this is especially usefull when filters are "remembered" in the user's session.
In this wiki I will show how could wo pass the third parameter to UserIdentity on login authenticate. So we can do separate login authentcation from two or more different models from single login form.
On my experience in Yii IRC, once in a while there would be someone that asks about how to create pages that handles 1 main model and its submodel and saving the changes in a single click. i wrote the example application on top of Yii2's basic application template that you can download here (i suggest you also run the acceptance test to see it in action):
Dynamic Tabular Form App