0, since you are traveling on separate reservations.
If traveling in the same reservation, you are eligible for 1 companion to be upgraded with you (at the highest status' clearance window and priority in the reservation) as long as both are Skymiles members.
If you are traveling on separate reservations, you can link the reservations but you will clear at your respective windows and priorities.
From:
http://www.delta.com/content/www/en_...lus-faqs.html: (underline mine)
DOES MY COMPANION HAVE TO BE IN THE SAME RESERVATION TO BE ELIGIBLE FOR A COMPLIMENTARY UPGRADE TO DELTA COMFORT+®?
Yes, your companion must be in the same reservation to be eligible for a Complimentary Upgrade to Delta Comfort+®. Clearance priority will be based on the status of the higher-tiered Member in your reservation.