Is it permissible for a husband to leave his first wife for the duration of his travel with her, knowing that the reason for travel is necessary and concerns all family members?

If there is a common benefit for all in the wife's travel, and she must be accompanied, then the duration of the travel is not counted against her, and her days are apportioned to her upon her return. The Hanafis held that the apportionment (of days) during travel is not obligatory but rather recommended. If the wife's travel is necessitated for the benefit of others, then there is no obligation to make up the period for those who did not travel.