Just approach as a group.
My family (same basic composition) and I flew into Atlanta a couple of months back. We were directed to the APC machines. Those of us that had US passports put our data page on the scanner, my wife put her B1/B2 visa on the scanner.
Of course we got the big X on our slips and had to get in the line, but it was quick, a few questions about what we are doing, how long and we were on our way.
If it is your wife's first time to use a visa, you may get some more questioning, as my wife did the very first time.
But this is if your wife has a B1/B2 visa. If she is traveling on an ESTA or Visa Waiver, then procedures maybe different. Though you should still approach as a family.