TOPIC: Different Billing for the individual registration type

Ok, there's one question

We have two type of registration
1. Individual
2. Group

If I select a group registration type I can define the billing part which is not necessary someone who is taking part in the event, right?
It's quite logical. I can work with an agency which is making a reservation for a group of people (their own clients) and maybe this agency doesn't want to share the details concerning the price, payment status, amount due etc. The agency fills their own email address and the confirmation email goes to the agency.

The individual registration is ok, when a private person makes a reservation for his own and becoming a billing part also. So far so good, BUT!
What if the billing part is an agency and want to make a reservation for ONLY ONE client? All the confirmation emails will be sent to this only one member, but what if the agency doesn't want to share this information with the client?
Now there's no way to separate the billing part and the participant in the individual registration type.

Thus, I can see 3 choices:

1. To make possible group registration part accept 1 member (now 2 members is the limit)
2. To make possible select whether this 1 person is billing or not. If yes - everything stays the same. If not, one more step will be added to define who is actually the billing part.
3. To create the third registration type (say, Individual+ (billing and participant differs).

Also it's a good idea to create additional admin notification e-mail for Group Registration type. Now if the group registration is made I have a lot of empty fields above {GROUP_MEMBER} {/GROUP_MEMBER} tags, because the billing part doesn't have the same registration fields with the members.

Thanks