When your school's data has been uploaded via Wonde, you can download login slips on the Teacher Dashboard.
Click the button to the left of students, which will highlight all of the pupils in a class and then click on the link parents button. You'll then get a message like the one in the screenshot below. Once you click download, a letter will be generated for each child in that class.
This will need to be completed on a class by class basis.
On each letter there are a couple of one time only codes, which will last for 2 weeks. These letters can be regenerated at any time.
If one parent has linked to their child, they can also invite an adult from within the app, if they wish to.