Upon the filing of an answer, either the petitioners or the respondent nonconsenting parent may at any time file a motion to set the matter for trial. On the return date of the motion, both sides shall attend, and in the event that only one side appears, that appearing party shall notify the other side of the setting, by letter, with a copy for the court file, and the party who did not appear (in person or by attorney) will be presumed to have agreed to that setting.