Option 1: Create two separate mailings so you can define different Name format options
Process: You will need to create two different selection queries to break-out the mailings. You can use this query for constituents with the same last name and this one for constituents with different last names by either adding them as an additional filter or using a separate selection query with those fields. After that you can create two mailings within an Appeal and set different Name format options for each mailing to get the right Addressee fields.
Option 2: Use a single mailing and output the information you need so you can make manual corrections in Excel.
Process: You will want to ensure you add the Spouse last name and Spouse full name fields as output fields in your mailing. You can then use this method in Excel to speed up the process of manually correcting the records.
If you would like to see this become a feature in Altru, please vote on this idea in our Community. We encourage you to vote on this post as this is an opportunity to have a voice in the product development process. Our Product Management team uses a variety of methods to determine new features in Altru, and the ideas in the Community is one way they do this, so your vote helps Product Management prioritize the new features that we put into the product.