"Well, there are a lot of small things... The biggest, the one I might need some help with if you still want to, are any cases of wizards who fought Unforgivables. I thought maybe some of the Wizengamot records, or if she kept journaled notes..." And while Susan looked for those things, which may be useful so Hermione didn't feel quite so guilty about putting her on a task that she wasn't really here for, Hermione would search for the mysterious R.A.B. again and hopefully get some new leads in these records they hadn't had access to. If they didn't figure out the significance of the initials soon, they'd have to move on to some sort of second option, or they'd run out of time.
"You don't have to, of course. Just if you weren't doing anything." She'd offered yesterday, but Susan wasn't Ron or Harry - and hence Hermione couldn't force her to study when she didn't have to.