@Armsdale second vote for the REI Screenhouse, as @REI-JohnJ suggested! We've had ours for years and found it extra helpful when our kiddo was young!
An alternate tent suggestion would be the REI Kingdom tent (6 or 8). This tent is great for a number of reasons, but one specific feature your family might appreciate is the center divider wall that allows you to essentially divide the tent in half!
Have fun camping with those little ones! I found time always went so fast because our kiddo could be occupied for hours with dirt, sticks, grass, rocks...
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