Any Electricity supplier(s) who allow multiple supplies in one account login? (SSE -> OVO...)

Maintenance

For years I've used SSE as the supplier to multiple properties where we either manage the communal electricity supply, or sub metered supplies. I used SSE as using one APP or their website login, I have (or rather, HAD) a drop-down where I could easily switch between the multiple property accounts, which made it quick and easy to read, sub-bill, submit readings etc.

SSE migrated all our accounts to OVO in July. OVO have informed me that I now need separate logins to each supply, with a different, individual email adresses and passwords for each account. This is an adminstrative nightmare and massively time consuming.

Can  anyone please recommend an electricity supplier (other than SSE) who provide a single account login to multiple metered supplies? 

Thanks in advance! :-)