Thai nationality before travelling to Germany will need to obtain a visa, inbound from the German Embassy in Bangkok, Thailand. Otherwise, there will be an immigration base from pinch (penalties of imprisonment of no more than 1 year) and Germany will not exceed 90 days within half a year, meaning that one year will be allowed no more than 2 times.
Minor children (under 16 years). Need a passport and visa, as well as adults and must receive consent from the parents.