Redmine

I'm in the process of evaluating Redmine. A feature that seems to be missing from a project management point of view is to move several issue a given amount of time into the future.

The following example illustrates the use case:
1. You have a project with a given start date and deadline.
2. All issues have defined start date and end date. Dates are specific to each task and based on estimated amount of work.
2. The project is delayed for some reason.
3. All issue and project dates needs to be moved 1 month into the future.

Currently step 3. seems to need manual setting of each issue. It's only possible to set the same start date and due date for several issues at the same time.
What I would like to see is some kind of relative increase of start/due date.

Does such functionality exist? Is there a better/preferred way of achieving the same result?

Edit: Running Redmine 2.4.2.stable from Ubuntu 14.04

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Torbjørn