Not being an expert in Thai contract law I decided to look at what effect is given to prenuptial agreements in Thailand. I found that generally speaking, so long as the Prenuptial agreement is registered at the time of the marriage the courts in Thailand will uphold the agreement.
The CR-1/IR-1 (CR-1 if married less than two years, IR-1 if married more than two years to your Thai Spouse) visa is an immigrant visa, the holder of which is lawfully admitted for permanent residence immediately upon arrival in the United States.
When a US Citizen sponsors a Thai fiancé/fiancée or spouse for immigration to the United States the US Citizen must show that he/she can support the Thai immigrant. The US government is interested in making sure that an immigrant brought to the US (for our purposes a Thai loved one) will not become a public charge (welfare recipient).
An IR-1/ CR-1 Visa is essentially what to use if you want to get your Thai spouse into the United States with permanent residence (green card). See the other options such as a K1 Visa or a K3 visa while in Thailand.
Advance Parole gives a Thai fiancée the right to re-enter the United States on a K-1 Visa after leaving the country. This is important because your fiancée cannot leave the country on a K-1 Visa and return without obtaining this crucial travel document.
Essentially a K3 visa was designed as a fast alternative to the immigrant visas (IR1/CR1). K3’s are a non-immigrant visa so one cannot stay indefinitely in the United States on one of these visas. For the Thai/American couple looking to immigrate to the USA, the K-3 is a good choice if time is of the essence.
Before getting into the K-1 process I would always advise obtaining competent legal advice from a licensed American attorney. Thailand can be very difficult to start the process however thousands have completed the process without many problems.