If she's not a US citizen ,, or legal resident. she dos not file
If her Thai earnings are listed under her Thai name.. not your sur name . you definitely do not want to open that box
don't forget you may need to submit an FBAR form for all total bank savings over 10k US
and if there are any accts with just her maiden name .. they will not be shared with the US
IF you have a legal US address that you can use while living oveseas . there is a huge savings /refund available for you