On the main settings area on Chimpegration Classic it is possible to configure the way in which a list handles constituents and non-constituent relationships.
There is no requirement to set up a list to accept relationship records. If you want to export non-constituent relationship data (usually non-constituent spouses' email addresses and merge variables) or want to synchronise this data then you should use this functionality.
On your list you need to have a merge variable that can have one of two values representing whether or not the subscriber is a regular constituent or a non-constituent relationship. This is so that Chimpegration Classic knows how to handle the subscriber and sends the correct information to it.
You can set this up in MailChimp as follows:
On the list go to the List fields and *|MERGE|* tags area.
Press the Add a Field button.
Select either Radio Buttons or Dropdown (it does not matter which as this will not be shown to the end user)
Fill in the fields as below. Note that the actual values do not really matter as long as they are meaningful to you. It is also possible that the merge tag i.e. MMERGE4 in this case is used by another merge variable. This is not a problem. Just accept the default value as shown or change the value to something useful to you.
Press the save button.
You will need to restart Chimpegration Classic for this to be seen in the settings area.