Question

Will states Dau Desire now wife of John Brown. Where is proof

Comments

The will on the page you've linked to is for the father of Jonas Hewitt's wife, Comfort.  

The Desire mentioned in that will Was sister to Comfort. She is called Babcock not Brown. Please clarify your question. 

Answer 1

One would suppose the will, being a legal document, attested and etc would be sufficient proof and in many cases it has been used so, court cases over inheritance for instance

But I suppose you mean where is there also a marriage record? you would need to do some research in the Parish / province / county / local church registers