You shouldn't have anything to worry about, since milk production increases to keep up with demand. This is why it's possible for a woman to feed, say, twins. When the baby is no longer breastfeeding, the breasts stop producing milk.
The only problems you might encounter would be extremely short-term, unless your wife has supply issues. If this is the case, a lactation consultant can be of help. (Visits with one are covered by many insurance plans.)
Strategies to ensure a healthy supply include pumping while away from the baby/babies, and massaging to express milk. For more information: Maximizing Milk Production with Hands On Pumping