writer: fixed automatic text at beginning of paragraph

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You can use a custom list style for it. In dialog tab Customize set Number to None, set Before to the desired name and After to the desired delimiter, likely a colon. In dialog tab Position set Tab stop at and Indent at to the same value and so large, that it is wide enough for the name.

If you need such named paragraph, you assign the list style.

You can go further and make for each person a paragraph style, where you set the so defined list style in the part Numbering in the tab Outline & Numbering in the paragraph style dialog.