Singapore's Policies of Assurance Act 1867 sets out how life policies are assigned. Section 5 deals with the form of an assignment: an endorsement on the policy, or a separate document. Section 3 deals with written notice to the insurer, and lets an assignee who has given notice sue for the policy money in its own name.
Nominations are governed separately, under the Insurance Act 1966. A revocable nomination generally ends when the policy is assigned, while a trust nomination usually means the trustees must agree before anything can happen.
This is general information, not legal advice. Whether a particular transfer works depends on the law, the insurer's rules and the policy itself. Read the Policies of Assurance Act 1867