If the spouse jumps in, then instead of one person in the water, you now have two to find. That may be fine for flat seas or a lake, but when the swells hit 4ish feet (+), it becomes difficult to keep an eye on that person overboard.
I propose the following: Instead of your wife jumping in, have her keep a constant watch on the KOB (Kid Overboard) while you do everything in your power to shut down and redirect the boat. Now you have four eyes to retrieve the child instead of two. SHe never takes her eyes off of the KOB. THat is important. SHe doesnt help sail, or motor, or pull off sheets. All she does is watch the child.
That is our MO. I would suggest tossing over a lifejacket in 4+ foot seas and watch how quickly it dissapears without constant watch. I cannot imagine the stress of having to steer the boat, turn her around, etc and then find two people in the seas.
You might consider a MOB pole as an alternative to the wife jumping in. THere is even one that pops out a lifejacket as I recall. Saw it on a post in Sailnet I think. Here is the standard:
Plastimo - Telescoping Crew Overboard Pole - Orange Floats - 48875
If you have trouble being comfortable sailing with the kids on board as you are very worried about losing one, you could invest in one of these. It seem to be the ultimate for safety and protection:
RAYMARINE LIFETAG WIRELESS MOB W/BASE STATION AND - E12185
Just my opinions and some thoughts.