What to do with…

For years I used that material for ground cloths under expensive tents. Use it coated side up to preserve the coating. I backpack for more than 30 days per year and one of these ground cloths would last for 5 or more years. Use a blade attachment on your soldering gun to make a nice hot-knife cut.

Denis, thanks for the response- that is what I bought the material for in the first place but I don't use any of those tents any more.
I don't want the fabric to go to waste!

1.9 oz urethane is usually very waterproof, so could be made into lots of things. Bivy floors of course, but also rain mits, rain chaps, poncho-tarps, etc. The extra weight over silnylon is not that significant. Especially if you are making custom sized gear for kids.

Oh, and poly ripstop will usually not stretch when wet like silnylon, so tarps will stay taunt in the rain. Even if tarp/bivy camping is not your thing, a tarp can be nice to have for hanging out in the rain, or keeping gear dry without having it in a tent.

If nothing else, you could sell it on the Gear Swap.

Man, I love finding extra stuff! Ok, so the material weighs more than 0.6 ounces… who cares? If you compare the weight of your 1.9 oz to 1.1 oz sil for, say, a 6×9 tarp, you end up with less than a 5 ounce difference. If you've got a lot of kids, why not make up a couple of tarps, maybe throw on a couple of beaks? Or a bomber mid? Use the material as flooring, buy a little noseeum netting and make individual or 2-person bug shelters for use under a tarp? Cheers-