How do I add a wife to my dads tree?
Thank you for posting in the Community about adding a spouse for you dad..
If you have access to his Tree, go to his details page, scroll down to the Family Members section, and above his name click "Add Spouse". It is the same if you are working on your Family Tree. The article link below may be useful.
Unfortunately, the article assumes the spouse to be deceased. If still alive, you will have to add her with a "Living" status and be aware that nobody but yourself can view any living individuals you add to Family Tree.
Any other relative wanting to add a profile of a living spouse in your "dad's tree" will have to create a separate "version" of her - which you will not be able to view. As you do not appear to be talking specifically about a spouse of your father, she could well be deceased and there should be no complications in following the article for which Sanra has provided the link.