Grow a Visio shape (e.g.a rectangle) based upon a start and end date

I need to create a project timeline diagram that's dynamically linked to data from an Excel spreadsheet.

What I'd like to do is to create a master shape (coud be a line, or a long thin rectangle for example)  to indicate project duration e.g. 01/09/2014 to 31/9/2015 (dd/mm/yyyy), and then have other shapes 'refer' to this as a baseline so that the start and end dates associated with their individual parameters do two thngs;

1. Position the start of the shape at the approximate location in relation to the master timeline.
2. Display the length of the shape as a calculation between the start and end dates, so for example, between 1/9/14 and 30/9/14 whould be shorter than a shape with dates of 1/11/14 through to 30/6/2015.

Anybody got any ideas how this can be done?

Ideally I want to do this with data graphics so that other parameters can be represented, e.g. progress, status etc.

Kind regards

Steve (London, UK)