I understand Thai culture enough to know that Thai families have strong ties.
If we like eachother enough to get married, I understand that it comes with obligations to care for and support your mother and daughters.
I would help raise your daughters as my own and I would expect them to live with us.
It is also important to note that I am not rich, and there is no job security here. I may need to change jobs in the future. There is no guarantee that I can work in Thailand either. If you hope to marry a wealthy man who can easily provide for your family for life then I have to disappoint you.
In Dutch culture men and woman are equal partners, and it while wages are higher here in the Netherlands, costs are also higher. Both man and woman need to work to support a good family life and education for the children. I am expected by my family to also have children of my own. If you are not prepared have to have more children, you may want to reconsider.
I also hope you understand that immigration rules for both Netherlands and Thailand are tough and complex, we might not be able to live together for a while. Procedures could take more than a year. A relationship between people from different countries requires a lot of effort. I hope you understand.