Your company can be exempted from the job advertising requirement if you need to transfer staff from an overseas branch for a short-term contingency (i.e. period of employment in Singapore is not more than 1 month).
However, the Employment Pass (EP) or S Pass holder will not be eligible to renew their work pass nor apply for a new EP or S Pass for 3 months after the expiry of the previous work pass.
If you need to bring in foreign staff for a longer duration on an EP or S Pass, you must meet the advertising requirement.