My client want to track customer comes from another domain(web property) and vice versa. Any suggestion by considering that the other domain (webproperty) belong to another partner and I dont want to give access to my webproperty.
I read that is possible to extend a webproperty, is it feasible? Below a picture to sum up my goals
You probably want to make use of campaign tracking instead.
Links from Domain B to Domain A would need to be tagged with the appropriate campaign tracking code. Then in Domain A's Report Suite, you'd be able to segment out traffic from those tracking codes, knowing that they're from your partner, and analyse them.