How to update SSIS package template

Hello Experts,

In my project, we use a standard template for SSIS package development. This template contains some common variables, connection managers, etc that are constant across all the packages in the project. Every time for a new SSIS package, we just copy the template, generate a new ID for it, do the additions required and save it.

Let's say, we need 200 packages in total. When the development is half way done, we identified that there needs to be some change in the template. Off course, for the remaining 100 packages we will use the new version of the template, but what about the already made 100?

Do we have to manually change in all the already developed 100 packages, or is there a way out?

What I can think of is, using .NET code, we can actually go inside those package's xml code and do the necessary addtion/modification/deletion. Can somebody provide the code to do this? Also, Is there an alternate way to do this?

Thanks,
Sudhanshu.