Need suggestions to creatively wholesale a deal

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Example of Problem: 

property is being wholesaled for $100k with seller asking $90K

buyer has $85k cash now. I'm sure i can get the seller to accept this but that would cut me out of my share of the deal.

Question: 

how can i creatively ensure I get my profit from the deal? Lien? part-owner until my share has been paid?

Hope I'm explaining the situation correctly, any suggestions and advice would be greatly appreciated.