procedure on reserving prescribed information

Tenancy Deposits

I need to reserve prescribed information on the tenants following ending of previous agency agreements and transfer of funds to a new account with tds. The tds website suggests that that you do not need to serve the deposit protection certificate with the prescribed information but your guidance suggests otherwise. Which is correct? Also do each of 2/3 individual tenants need to receive their own separate copies of the certificate ( if needed- see above), the prescribed information and scheme booklet or can I send one copy of each for all individual tenants? Also how should I go about obtaining proofs of receipt/ evidence of service? Should the documents be handed over in person (difficult with the current restrictions) or put through the letterbox? is email sufficient? Please provide a "step by step" guide.