We are using civi to help us fundraise for our school. Each year we upload the new parents to the database from a csv from schoolbase. We need to add a relationship for each parent to their child(ren). This is important, because the communications we send vary based on the children's D.O.B (this enables us to tell which school year they are in without updating it every year). Is there a way to import these relationships at the same time as importing the contacts? Is this just a question of using correct field mapping? If they have more than one child would you need to have all the children in the same field? I'm assuming you'd need to import the children separately first, is that right?
Welcome to SE! Yes, you can import the relationship at the same time. The documentation describes your situation here.
This is based on one row per child with parent details in the columns. You import once for child, mother, relationship and once for child, father, relationship.
Check that your default dedupe rules work for the parent fields you are importing to avoid duplicates being created.
You don't need to do anything special where more than one child has the same parents other than check the dedupe rules. Each child is a separate line.
I'd suggest trying this on a test system first to become familiar with the process and check your dedupe rules are working as desired.
Try following the steps in the documentation and let us know if you have further questions.