No. You wouldn't need to ask existing parents (parents of children who are already enrolled at your centre) to register with you from scratch. You can do the following instead:
If you already have children added in your 'Children's Register', you can generate new registration forms for all those children and auto-sync their basic details into the new forms.
1. Go to your 'Registration Dashboard'.
2. Click on the 'Sync Children's Register' button.
New registration forms will be automatically generated for each child and added to your dashboard with the basic details exported from the 'children's register'. But, there will still be more fields and the 'consent' section in these forms which the parents will need to edit and update.
As these newly created forms will be in 'locked' status, by default, you will need to unlock the forms first and then invite the parents to edit and submit them. Here's how: