Bippette beat me to the punch ...
Having taken a placement of a child similar to this one's needs (not being aware of them until after placement though) and seeing first hand the effect it has on the family and other children in the home, my advice with your family make-up would be to RUN. This child needs to be placed where he is the ONLY child with two parents and a great support system and get 100% attention - where he won't be competing for that 100% attention! ... know this is probably not what you want to hear but ... AND, this placement disrupted when we couldn't protect the other children nor himself from himself which then put us in jeopardy of being charged with neglect ... another long story in itself but something for you to think about.
Best wishes with your decision - whichever way you go - this board, including me with this placement that didn't work, can help with advice, knowledge and most of all shoulders and support - something you will need lots of!
Keep us posted!