I am a divorcee. How does a Will affect me in terms of guardianship of my children?
On the death of the father/mother of an infant, the mother/father, if surviving, shall, subject to the provisions of the Guardianship of Infants Act, be guardian of the infant, either alone or jointly with any guardian appointed by the father/mother.
Additionally, the father/mother of an infant may by deed or will appoint any person to be guardian of the infant after his death. Any guardian so appointed shall act jointly with the other surviving parent, unless he/she objects to the appointed testamentary guardian so acting.
If the surviving parent objects to the appointment of your appointed guardian OR your appointed guardian deems the surviving parent unfit to have custody of the infant, in which case they have to apply to court for the issue to be resolved.
Source: Singapore Statutes Online Website, Guardianship of Infants Act
In the case where you are divorced and have worries with regards to your kids' welfare if taken care solely by your ex-spouse (who is the parent of your children), you can appoint in the system to have a guardian to act jointly with the other parent. There is no difference of priority in terms of making decision for the children between your appointed guardian and the other parent.
If you have no worries and fully entrust your ex-spouse (the other parent) to be the sole guardian, you may also select the "No guardianship clause" or the "To act only if no parents survives" depending on your preference.