To assign a slot to a parent who is not on Bloomz - 

1. Click on the Class name in the left navigation tray
2. Click on Signups in the Updates tab
3. Click on your Parent Teacher Conference
4. Scroll to the desired time slot
5. Click Sign Up 
6. Select yourself in the Sign Up text field
7. In the Personal note to teacher, type the name of the parent for whom you are booking the slot
8. Click Sign Up