Mmm, true.
It's too bad they already sent a message to c, lol.
It can't be directly at one planet... They wouldn't try that, because we don't know the orbits that well, and the f and g solution changes the orbits of every planet.
I came up with a 7 planet solution (yay for h) but I think one of them is really useless... lol
Here is the thing I came up with... Odd that mine looks oddly like a mix of them... it'd got c, then g, but d on it's eccentric orbit...