I know it's pointless since the fic is long past complete, but I didn't really get or agree with all the thing sirius is giving up to the malfoys here.
He's giving up his relationship with his own godson, not even being there for his BIRTHDAY, for time with the worthless little shit draco. He's giving up making draco co-heir, which translates as giving half the black estate to voldemort.
None of this makes sense, was all that crap in exchange for dobby? If so, sirius/harry got screwed, they could have given up waaay less.
It reads like a deal fucking dumbledore would make, give tons of stuff to the malfoys all on the tiny chance that maybe draco can be 'saved'.
It's bullshit. Even if it's some scheme to get the diary, I don't get it. Hell harry knows where the stash of dark artifacts is, and in the other timeline arthur raided malfoy manor. So give the tip early, provide the location to the stash, likely get the diary AND cost malfoy some money.