The reason I said a relevant US Dept is because I believe, judging by Schapelle's case, that politicians and other govt staff seem to have the most power and pull with Indonesian authorities. Non-Indonesian lawyers have no bearing at all in Indonesia. And, yes, family is usually the driver behind those govt efforts.
And as Highandmighty said above, what about the baby's rights within the context of being a US citizen? While that may not count to Indonesia, surely they mean something to the US law and someone (political) could extend themselves for an innocent minor ... a newborn baby.
ETA: I by no means mean to detract from the horrible murder of Sheila, I just think that the baby should be pulled out of there as an innocent US citizen, and that HM and TS should both receive and carry out the full sentence deserved by them both.
As you can tell, I am very passionate about the protection of little children. I'll try and keep that passion more muted from now on.