Can one change the datetime an item was added to a sprint? Right now the scope change is recorded when it is done, but i would like to pretend an item was in the sprint all along. Does this functionality exist anywhere?
It's possible to change the date or time on a scrum board, however you will need admin permissions on the project.
Here's a link with more detail.
Short answer: No :)
sorry but if we look at the understanding of a sprint its fine to add and remove items but what you are doing is manipulating the stats probably to improve your burndown?
I would advise against this.
Good luck in your endeavors :)