After clearing the area from hostiles you will proceed to another area that will look like this.

Now go press that button next to the shutter door and go pick his ass up.
Yes Dave is a cardboard box and wants you to find his family.

The room where you reset the power after turning on the 3 valves.
Look under the desk, you'll find the first child.

You will come to this next area and you'll eventually encounter some guards.

You will hear a shutter door open.
Turn your ass around and eliminate the scrubs trying to do a pincer attack.

You found Abrigail Shapiro! wait wrong mommy...
Congrats you found Dave's wife, you clearly see how happy she looks being rescued

Eventually you'll be at the server room where all [REDACTED] 's porn stash and this facility intel is. Proceed to go straight ahead to the Archive door and go left downstairs. Make sure to clear the area of hostiles.

Once you go through the door you'll go left downstairs. Look around and you'll find the other child hiding down here in the left corner of the room.

Dave wants to give you something for your gratitude. He is appreciated to be back with his family.
Here's a picture of his ex