Can I rely only on Faraid? Is Faraid sufficient for all family structures?

You should not depend solely on Faraid without writing an Islamic will (Wasiat), as there are many other roles of Wasiat besides the distribution part of it to non-faraid beneficiaries, especially on the appointment of executor(s) to take the lead in administering the distribution by Faraid.
It is especially important for families with members that are not covered via Faraid, to plan their estate by using tools such as Wasiat or hibah (CPF & insurance nominations) to complement Faraid.
This category of people include: adopted children/parents, foster children/parents, children out of wedlock (for biological fathers), non-Muslim relatives, or even siblings who do not receive any distribution through Faraid, etc,.
For more related questions, visit: https://ask.gov.sg/muis.