Authorisation object for restricting access to XD01-XD03 and VA01-VA03

Hi, Experts

I want to restrict the authorisation for the above mentioned transactions

The authorisation restriction requirement is as follows

1. The end users of SAP should have restricted authorisation to perform

Sales related transactions based on the authorisation group

2. A user should not see the sales data of the other user

3. Each user is restricted to perform sales transactions w.r.t a group of customers

4. The group of cusotmer will be defined

Please help me

Thanks in advance

Venkat