use SilverStripe\Forms\FieldList; $fields = new FieldList( TextField::create('FirstName'), TextField::create('LastName'), TextField::create('Email') ); // Insert a new field before the 'Email' field $fields->insertBefore( TextField::create('Country'), 'Email' );In the above example, we created a field list with three fields and then inserted a new 'Country' field before the 'Email' field. Package/library: SilverStripe Framework.