Please include the option to add config to the existing subscription!

[javadgh6]

Feature description

In the current version every time we add some new configs it is added as a new subscription. Please enable to add new configs to the existing subscription. Please also enable to hide or delete invalid configs in a subscription.

[UbiVPN]

Since it is a subscription model, the obtained configuration should override the previous configuration.

[kekomenos]

Since it is a subscription model, the obtained configuration should override the previous configuration.

[TitanComputer]

PR welcomed