Learning loads about YAML and now it's working - sort of.

db/migrate/20230127131552_add_condition_to_sub_principal_item_groups.rb

@@ -0,0 +1,5 @@
+class AddConditionToSubPrincipalItemGroups < ActiveRecord::Migration[7.0]
+  def change
+    add_column :subprincipleitemgroups, :condition, :string
+  end
+end