Forced adoption?

I never knew that I would want to adopt another child. Let alone, an older child (older than my oldest). I have fallen in love with my neighbor's son. He is 7 1/2 years old, and just the most adorable little boy. The part that breaks my heart is that he seems to be completely neglected. His parents both work in the evening, so he is left with his teenage sisters (ages 14 and 18) all the time. These poor teenage girls are forced to care for him like mothers, pretty much. Therefore, he is allowed to roam the neighborhood by himself, watch inappropriate movies, and parent himself. Since meeting him, he has been over here for dinner a lot (not that I mind - I just love him), and he always eats up everything with such great manners like he never eats :( Elizabeth is IN LOVE with him, and wants to hug and kiss him all the time. He plays so wonderfully with all three of my kids, giving them piggyback rides and making them laugh. My boys idolize him, and can't wait to see him every day. I just want to ADOPT him, seriously. And to top it all off, he told me yesterday that my house is "better than Disneyland!" Do you think they'll notice if I keep him (haha just kidding)?