Registration under reverse charge

Dear All, A new concern has registered for service tax as service providers and service recipient. While they have mentioned the category of service provided but havent mentioned the category of services which they expect to receive. My query is:

1. Can they select 4-5 services which they expect to receive but are not currently receiving?

2. How do they amend the Form ST1 as they have still not received the ST2 (recently applied)?

Would appreciate a quick reply thanks.