You and your wife can give that kid a life that is far better than anything he would get in foster care, but you have to ask (given your age and the lack of siblings this kid would have to grow up with) whether that young couple could give him a life that is actually better than what you can provide.

I don't know the answer, I'm just saying it's something you have to consider. In other words, if the alternative to you taking him in is still a really great alternative, then that changes the calculus somewhat. Especially if there would be an avenue for your 5 daughters to maintain a connection and relationship with him all along the way. Frankly, they are so much older that such a dynamic might not be too different than what it would be if you and your wife adopted him.

I don't know if that other couple lives near you, whether they are members of the church, or other information that may matter. Just something to think about as you ponder.