The Roku Channel LiveTV is a seperate entity. It includes a compiled collection of channels that is either leased or provided to them. ABC is currently not included in the Roku Channel Live TV offerings. ABC News used to be in the guide, but was removed about a month or so ago.
Adding standalone channels/apps from the Roku Channel Store (ie. adding channels/apps to your Roku device Home Screen) will have no affect on the Roku Channel Live TV.
In order to watch ABC "live", just launch the ABC channel/app you installed and go ABC's LiveTV guide. Keep in mind that the Live TV offered is usually not the same as "live" you would receive on antenna/OTA (or when you watched your locals on cable TV.) The LiveTV in streaming is generally just continuous content from a network's library, or a repeated showing of that days news if watching a Live TV news programming (ie. ABC News). All depends on the channel/app.
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