Batch Property Update
If you have created a dozen SSIS packages from your template SSIS package, then you realize a property in the template you forgot to set, the Batch Property Update feature can help.
Multi-select (with Ctrl-click) the packages in Solution Explorer you wish to change, then choose the Batch Property Update menu:
Then the following window pops up. Use the help text at the top to set the path and new property value: