Again I agree with you Morloth.
I think they have to, in humane terms, allow any current surrogacies to go ahead otherwise it would be ridiculous - as you say, Thai surrogates left with children who are not biologically theirs, whom they are unlikely to be able to afford, and who are at risk of prosecution.
I think the Thai govt has to decide in humane terms that this particular mother should either not be prosecuted, or, if prosecuted at least not given jail time - otherwise what would become of Gammy and his siblings then?
An amnesty is the most humane way forward, with an immediate brake on any other cases - if frozen embryos are involved, then there should possibly be some way these could be returned to the biological parents, but they should definitely not be implanted as of now (or in fact, as of a few days ago when this story broke)
I hope they find Gammy's sister and I hope that they remove her. If she is an Australian citizen now there is next to no chance that she will be returned to Thailand, sadly; but if the parents failed to register her properly then there might be a chance.
In all of this, the relevant govts have to keep in mind what is best for the children - and prosecuting the Thai surrogate mums isn't likely to be the best for any child, or other children risk being left without their mum.
The clinics/agents however - prosecute them til it hurts. They're the ones taking advantage of vulnerable people - desperate would-be parents at one end, and poor, needing money at all costs women at the other end. THEY are the ones who are guilty of human trafficking and they should be prosecuted as such.