1) Since your family already has a valid tourist visa for Thailand, the main documents they’ll need for the Bhutan leg of their trip are their passport, the Thailand visa, and any documents for entry into Bhutan, such as their Bhutan travel permit (which can be arranged through a tour operator). When I traveled through Bhutan, I used matrix.in for visa-related questions, and they guided me on the necessary paperwork.
2) Here's what they will need:
- A valid passport with the Thailand tourist visa already affixed.
- Bhutan travel permit (this can be obtained either online or through a licensed tour operator).
- Proof of accommodation or tour itinerary in Bhutan.
- Return flight ticket from Paro to Thailand (as evidence of onward travel).
I found using matrix’s assistance helpful when organizing travel permits and visas, ensuring everything was sorted smoothly.