HI Panduranga,
for what you are trying to you should use BOL programming (How To Guide Business Object Layer Programming) instead of the ORDER function modules or BAdIs.
Depending on you requirement (e.g. do you really wnat to change data or do you want to display a transient property) you could use the model classes in the CRM UI to perform the checks. I would recommand carefully considering the requirement. A user usually doesn't expect/accept a behaviour where he/she wants to display an object and this already leads to data changes.
Christian