Both parents want to follow along — can there be two logins?
Yes. One family may have more than one contact, each with their own number and their own PIN. Both open the same Parents Portal and see the same children.
Each contact's relationship is recorded — father, mother, grandparent, guardian, and so on — so staff know who they are speaking with. School messages go to the registered contacts, so adding a second one means the news reaches two people.