Transfer thai - Laos motor bike registration

Hi I am after good information not what your heard as there is many story’s in Thailand.

My wife has 2 motor bikes in her name a 150cc and 250cc.

She moving back to Laos next year and we want to keep bikes as we look and buy same in Lao but they are double the price of thailand.

1-So do anyone know how long they must be registered in her name before she can take over to Laos if any ?

2-Does the import tax differ on price she pays of market value or prices of bike brought at ?

3-And and does price of tax drop if she own bike over 12 months in Thailand

I hope to have a good guild line before I take it up with land & transport office in Thailand & Laos if anyone has done please reply.

Johnnybgood