Taking nephew nad Niece

All information about visa can be found on www.ica.gov.sg and http://beta.mom.gov.sg/passes-and-permits
In short: You can only sponsor long-term visa for your spouse, children, parents (and that only if you earn above the thresholds), but not for your sister or her children.
They would have to qualify for a visa on their own merit. If she gets an S-Pass and earns above S$4000/month, she can get a DP for her children. Alternatively, if the kids are accepted by a Singapore school and get a Student's Pass for that, she can accompany them on an LTVP - but she cannot work then!

beppi wrote:

All information about visa can be found on ica.gov.sg and beta.mom.gov.sg/passes-and-permits
In short: You can only sponsor long-term visa for your spouse, children, parents (and that only if you earn above the thresholds), but not for your sister or her children.
They would have to qualify for a visa on their own merit. If she gets an S-Pass and earns above S$4000/month, she can get a DP for her children. Alternatively, if the kids are accepted by a Singapore school and get a Student's Pass for that, she can accompany them on an LTVP - but she cannot work then!

Thanks for your reply and information.

It is clear that i need to get student pass for children. Do you have any idea about Singapore schools where i can enroll them.

As foreigners, they have a very low chance of being accepted in a public school. Thus you should contact private international schools and ask for entry procedures (and waiting lists, which many of them have).
Please note that private schools cost S$1500-3000/month (per child) - public schools would cost only S$500/month.