is this gramaticaly correct

Le, 

There are three notable errors.  

First, you don't have a subject.  What is it that is "hereby stating"?  It should read something that says:  "The contract hereby states that. . .".

Second, neither/nor plus "do not know", means that the seller and buyer know because the neither and not know aredouble negatives.  Perhaps you meant to say: "Neither the seller nor the buyer knows or is aware of any party. . .".

Third, 'possession' is spelled with two double-'es'.

I hope this helps.

Kim