Defaulting payment Term in AR Invoice

Hi All,

How I can get the Payment term From the Sales Order, defaulted in the AR Invoice ?

As the Payment Term for Different order to same Customer may change, we need to update the Payment Term at the Time of Creation of Sales Order. So payment term Need to be defaulted from Sales Order. Is this Possible. What will happen if there is Payment Term Entry at Customer Level, Customer Site Level and Price List Level. Is there any Provision to override these and get Payment Term from Sales order ?

Pls help...