reason I used Lufthansa is because I found out that all the high priced pet movers in the US used them exclusively. I couldn’t pay what they wanted because they obviously catered to the elite that didn’t own their own aircraft and wanted a serious amount of $$. But the sales team continued to contact me and each time giving me clues and hints about how they went about building the itinerary until they mentioned Lufthansa. Found out later that many of the exclusive zoos in Europe use them to transport animals back n forth to parts of the world.
Lufthansa is the best for animal travel. If you’re transitting thru Frankfurt even better as they’ll get a break at the animal lounge. Brought 2 adult GSD’s here and would/will NEVER use another airline. On both trips the service crew went and checked on them for me. Wouldn’t want to bring them in the cabin even if that was an option. Waaaay too much stress on an animal if they’ve never flown or been in tight quarters with strangers. Zip tie treats and food to outside of kennel and find a good water reservoir that can’t tip/attaches to kennel. Unless things have changed make sure you’ve communicated everything needed to Thai authentic before leaving. And depending on your impending arrival time make sure you have a pet friendly van service either already hired or get ready to deal with the local cabbies potentially turning you away cauz they don’t want to deal with transporting animals.
If they ever persist on a full month just goto Agoda and book with a big brand hotel that gives free cancellation. If they ever want a receipt just make sure the parameters of your booking allow for cancellation and a full refund. Don’t do this with small mom n pop places, only large name brands even though its more expensive initially, else you’ll find yourself in a virtual interrogation/refund struggle with booking agents because these smaller places are tired of getting burned. Many hotels drastically changed their cancellation policies after the COVID-ASQ days when the MFA wanted receipts for full stay (90 days in the case of Special Tourist Visa’s) with tax ID’s and nearly everyone was canceling these large bookings just to get approved.
in Ubon province they don’t do squat with birth certificates even for extensions. It might be different for other districts and I’d confirm via correspondence with any consulate before I hitched my wagon to a birth certificate. And depending on the family situation or where the mothers families are located he may not be able to make these runs so easily. But if his district allows only BC then it could be a temporary solution until he can get it sorted via the courts.
to add to that, I would also recommend him getting a lawyer, and it doesn’t even have to be a very good lawyer, or one that cost a lot of money, because the court is going to ensure that everything is done properly in the best interest of the children, which is clearly him becoming the full custody parent. It would probably help out in the end regarding his future Visa as well, if he had some sort of counsel to mitigate any further issues with immigration. 
if he’s taking care of both of the kids, then it should be an easy process for him to get legitimized as the father if he hasn’t already done so, and then petition the court to give him full custody and then aside from the stacks of paperwork and photos. Immigration is going to require him to submit. . And another thing aside from the birth certificate really meaning nothing
Per Thai law,
the court is still going to require him to have DNA test for both the kids and then it’s probably going to be about a three month four month process to get full custody if neither of the mothers are willing to cooperate, but Many here have done it and it just takes time .