Write the first initial of both last names in the middle of the monogram design space.
Write the first letter of the first name in a smaller size to the left of the last-name initials.
Write the first letter of the middle name in a smaller size to the right of the last-name initials.
Add artistic flourishes to the monogram letters as desired.
Write the first letter of the last name of one partner in a large font so the right edge of the letter is just left-of-center.
Write the first letter of the last name of the second partner in a large font so the left edge of the letter is just right-of-center. Together the two last-name letters will be centered.
Write the first initial of the first partner's name to the left of the last name letters in a smaller font.
Write the first initial of the second partner's name to the right of the last name letters in a smaller font.
Add artistic flourishes to the monogram letters as desired.