“The offer was made jointly to the first and second respondents and it is clear that the first respondent could not accept it without the second respondent accepting it as well. The consequence of the second respondent accepting it would be to render the second respondent liable to make payment in damages and for costs for which she was not liable. In addition, a consequence of the first respondent accepting it would be to render the first respondent liable for all of the applicant’s costs of the proceedings, including those relating to its unsuccessful claims against the second respondent up to the point of acceptance.”