To assign the form/registration groups for next year this can be done via Admin > Students > Group Updater.
In here you can select the year or form group for the form group you wish to set, change the student attribute to New Form for September and then Choose.
Once you have clicked Choose you will see a list of the students in the group requested, in the dropdown next to the Check All button select the form group they will be in next year (if you have new form groups next year please click here to view how to set these up), then click Check All (or select the students who are going into that year) and update at the bottom to save.
If the registration groups are being split up in September, once one form group has been set you would then complete the above again, selecting the other form group from the dropdown and checking the required students and updating at the bottom once complete.
Please note once complete you are able to check the information via Reporting > Reports > Students (tab) > Next Year's Form Groups.