Easier way to update custom variables to be shared across Stages within a Build Plan.

Consider the following scenario:

1. <Build Plan A>.<Stage 1>.<Job 1> ---> Update custom variable value

2. <Build Plan A>.<Stage 2>.<Job 1> ---> Use custom variable value from Stage 1

Currently the only way to achieve this is making use of the "Bamboo Inject Variables Plugin" and have the custom variables added to an external file - in order to achieve this we need to add a 'Script' task to Stage 1 to generate the variables and the file. From there we can create an artifact definition that will be generated as a result from building Stage 1. Now we can go to Stage 2 and download the artifact produced from Stage 1 that will contain the variables. After that we can add an 'Inject Bamboo variables' task to read the artifact produced by Stage 1 and create a 'Script' task (or any other task) to use the variables from the artifact. Every time we want to update the values of the variables we can go to the Script task in Stage 1, change the values inside the Script task and generate a new artifact that will be downloaded by Stage 2 and so on.

It would be nice to have an easier way to accomplish this task without having to use a plugin/external file containing custom variables so we can regurarly update them, something like a built-in feature.