Can we keep her?

I just recently started sitting for a 6 month old baby girl full time. I was explaining to the boys how I would watch her at our house while her mommy and daddy were at work. Blake was very interested in how big she was, how long would she be here, would she be here when he got back from school, etc. Baby J was here for about 10 minutes and the boys were absolutely enthralled with her and Blake says to me "now that I have seen how cute she is, can we keep her?" For those of you who know, he has been asking me for a baby sister since I was pregnant with Parker. Unfortunately, we can't keep this one!