How do I legally structure a deal to be the middleman in selling a subdivision?

[Roman Sari]

I know the seller of an approved 6-house subdivision (shovel-ready) which he wants $1.2M for. He is willing to sell it to me for $1.0M. My friend pitched the idea of us being the middlemen and selling it forward to an out of state relative who is willing to buy it for $1.2M and is aware we will make a profit being the middlemen, signing an NDNC. 

I'm not able to double close the property because of the 30% downpayment the seller is asking. How would I structure this deal? Should I just leave it alone? Any other thoughts?