To make a spouse an acknowledgee you will first want to open your profile that creates the tribute in IOM > Configuration.
Once there, here is a list of steps for mapping your profile.
1) Set all donor and gift-related information to Ignore.
2) Map tributee information fields as constituent fields.
3) Map acknowledgee information fields as relationships.
4) Include the field Individual Relationship > Tribute > Relationship is an Acknowledgee or Organization Relationship > Tribute > Relationship is an Acknowledgee with a value of Yes for each relationship in the data file so that these relationship records will be marked as acknowledgees.
5) Map the tribute type or other tribute fields such as description, default fund, date from, date to, etc if contained in the file.
This is an example of how the mapping should look.
Next make sure IOM knows that this is a tribute import by going to “Tributes” on the left navigation pane and selecting “Tribute Profile”.
Set the Tribute default options as they are appropriate for your import.
Here is a page from our User Guide that goes into further detail. https://omatic-importomatic.helpdocsonline.com/import-tributes-and-tribute-gifts$Import%20new%20tributes%20and%20acknowledgees