Connect two webforms? I have 2 webforms: survey webform and task webform.
The entry point is task webform and it requires user to login.
There is a controller or something to check if user has previously filled in a survey webform, if he/she did, go straight to task webform. Otherwise, need to go to survey form.
I know how to create webforms, but not sure how to make such controller.
I am not sure about your control here, whether to move from survey webform to task webform or the vice versa. But this is what I would do.,


On login query the "webform_submissions" table with the logged in user's id and see whether he/she has submitted the webform before.
If he/she has not submitted it before load the webform say task webform.
If he has submitted this before, load the survey webform page.


You can make use of "hook_user_login" to redirect on login, also this can be used to query the "webform_submissions" table.