In the Add Existing Item dialog that you get from Visual Studio's Solution Explorer, you can add a link to another file on disk to the project. In order to do this, you will have to click on the down-arrow on the right side of the Add button and choose Add As Link.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…