You can do this by adding a column to your excel with a comma separated list of groups to add a contact to, you will create multiple lists upon importing the Excel file.
if I have a groups column like this:
Person: A, Groups: X
Person: B, Groups: X,Y
Person: C, Groups: Y
And I import this as "MyList.csv"
This will result in two lists:
- MyList.csv X Person A Person B
- MyList.csv Y Person B Person C
Please note that the first Person B and the second Person B are only mere copies of each other. There is no relationship between the two.