We build houses, each house is a project, each project has differents task (electricity, plump, manufactured, etc), I just want to create sub task but related to each task. I choose the "label" functionality option to assign each project to a house name, but how do I create task and subtask for project, so as to see in the timeline view the subtask under each task agroup by label.
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Take a look at this article, it will show how it can be done natively in Trello:
I'm not sure that it can be fully achieved with Trello timeline but if you consider Trello power-ups, then you can do it easily with Planyway.
To view tasks and subtasks grouped by project labels in a timeline, integrating a tool like Planyway with your Trello board can be very beneficial:

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