You can access all of your ClassroomParent schools using a single username and password.
The key is to ensure that ClassroomParent can link your information between to two schools. To do this, when adding your information to the new school using the Student Contact Information form, enter the same first name, last name, and email address from the old school. ClassroomParent will use this information to link to your old school.
One way to check that this worked correctly is to leave the Salutation field blank. If the form is accepted, ClassroomParent was able to link your information. If it returns with an error that Salutation must be selected, then it could not match. Verify your first name, last name and email address are the same as that used in the old school and re-enter.