Kick off a rebalance in a pentagon swap

Hi, I'm node B in a pentagon swap. I'd like to try my hand at rebalancing the channels. It looks like I run an `addinvoice` and a `buildroute`. For that second step I need to plug in `PAYMENT_ADDR`. Is that address going to be to node C? Or A?

I'm also supposed to plug in `R_HASH`, I'm not sure I know what that one would be?