Who all can be witness

In a real estate transaction sale/purchase of property, lease agreement,

any body from your family members for eg. wife,brother,father ,mother  sign as witness for  husband,brother,son and vice versa, but if there are in- dependant witnesses, then it is better in any case.

So far as Will deed is concern you must have in-dependant two witnesses, who are not in blood relation...
 

as Mr. Mahesh has suggested that it will always better to witnesses the deeds from independent witnesses ,specially will deed always be witnessed by the two independent witnesses other than your family members.