Dual/Single supply Dimplex Quantum storage heaters

I am a landlord/owner of a flat. I am just about to spur off nearby sockets to provide the additional 24hr supply to new Dimplex Quantum storage heaters. Before i do some ugly surface mounted wiring I re-checked the heater installation manual. These Quantum heaters can be wired to a single 24hr supply and rely on their internal timers or wifi controlled timers to ensure they only come on during the E7 night hours - see attached. I have 2 pairs of tails coming from the old RTS meter. One pair for the E7 CU and other for the 24hr CU. So why dont i just put the E7 CU on the 24hr tails as well? The immersion tank has timers too which would be programmed for E7 times. All sockets etc switch to the cheap rate at the E7 times. So why do i need to struggle with adding spurs to nearby sockets when the CU can be changed instead? This RTS meter will be updated shortly so i need to make sure the new type is still compatible with this new 24hr twin tariff setup. OVO wont speak to me about the property meter and this switch over option because i am not the account holder but the tenant wont understand any of this to let them deal with it!