Forum Solution for Buddypress Groups besides bbpress / customizing bbpress

Hey.

following issue:

I want to use a Group forum that has tree post structure:

Forum Topic: What do you think?
2011-01-01 Reply 1: I think yes!
2011-03-01 Reply 1.1: I think Yes is Right
2011-02-01 Reply 2: I think no!
2011-04-01 Reply 2.1: I think No is Right
....

That doesn't be possible with bbpress. only:
Forum Topic: What do you think?
2011-01-01 Reply 1: I think yes!
2011-02-01 Reply 2: I think no!
2011-03-01 Reply 3: I think Yes is Right
2011-04-01 Reply 4: I think No is Right

Following Questions i asked myself and now you because i couldn't find an answer:
- are there any advanced options for bbpress which I can access through admin or hardcode?
seems like there are not really any settings. or do i have to install bbpress external to access the full settings?
- are there any plugins for bbpress existing that deal with the problem?
- Is there another Forum solution besides bbpress?

Thx for help / ideas / information!
Oli