private NumberingDefinitionsPart FindOrCreateNumberingDefinitionPart(MainDocumentPart mainDocumentPart) { NumberingDefinitionsPart result = null; var existingDefinitions = mainDocumentPart.GetPartsOfType<NumberingDefinitionsPart>(); foreach (NumberingDefinitionsPart existingDefinition in existingDefinitions) { result = existingDefinition; } if (result == null) result = mainDocumentPart.AddNewPart<NumberingDefinitionsPart>(); return result; }