I think Lily Aritama has it down pat.
A "sponsor" is a pseudo-employer, i.e. who appears to be the employer but does not satisfy the real meaning of employer.
An employer of an foreign domestic worker
a) pays her salary
b) pays the foreign workers' levy
c) gives her food and lodging gratis
d) requires her to work full-time for her and ONLY for her.
In other words the maid who works for a REAL employer (not a sponsor) will work only for the REAL employer and nobody else (which is against the law).
A sponsor merely pretends to be an employer. He/She applies for a work permit for the maid. As far as the Work Permit Department is concerned, she is a REAL employer. If it subsequently shown that this sponsor permits the maid to go out and work part-time, then the sponsor (or the fake-employer or pseudo-employer) is in for a tough time. He/She will most likely be charged in court for cheating the Work Permit Department and the Immigration Department.
She will be charged for illegal deployment (letting her work elsewhere for someone else.) The Work Permit Department has made it very clear, the foreign worker (domestic or otherwise) may not work for anyone other the employer; she may not perform any other duties except the duties normally performed by a domestic worker; she may not work in any other location other than her employer's house. In other words an employer of a foreign domestic worker may not ask her maid to clean up her office.
If you do not want to run foul of the law, do not employ a foreign maid on a part-time basis. You can always employ a local part-time maid.
Please visit my website: http://www.lucky.com.sg/intermares/phtm/singfaq.htm
where I have a Q&A page (Frequently asked questions).
[This message has been edited by BoardManager (edited 07-03-2001).]