Addressing second charger with set_charge_rate service.

[rbb-dev]

It seems that set_charge_rate can only address the last charger configured/connected.
Can the set_charge_rate service be changed also to allow specifying the charger serial and, if not sent, using the current behaviour?
This would allow us to address the second charger and won't break the current installs.
Something like this for example:
limit_watts: 10000
conn_id: 1
charger: 3e95

Or is there a better way?
or maybe registering the services under domain other than ocpp?
Maybe register them under same domain as the start charging buttons?