You can either:
a) Write to us with clear photocopies of the relevant documents to

Central Provident Fund Board
79 Robinson Road
CPF Building
Singapore 068897
Member Accounts Services Department
(Ref: MAC/UPD)

b) Submit your application via my cpf Online Services - My Requests > Other CPF Matters > Update my personal particulars using your SingPass or

c) Visit any of our CPF offices with the original relevant documents