Make it easier to handle (similar) custom expressions in different visualisations

Please make it is easier to change mutliple custom expressions and reuse custom expressions.

Example 1:

When I've three bar charts with different x-axis but with the same y-axis I want to change the custom expression at 1 place so that I'm sure the same definition is used at different places. Currently I should create a document property containing that custom expression but it is not easy to work with them when the custom expressions are very long. Besides it is difficult to keep the overview when there are like 100 document properties.

Example 2:

I've a report about flight prices. First the price used in the table is the price per passenger. Later on the column changes to total price of booking and now I've to divide the total price of booking by the number of passengers in every expression. I want to easily search for every expression where this column is used, or replace all parts where that column is used at once.

Possible solution

A possible solution would be to have an overview of all custom expressions in the document/on a page. In this overview I should also be able to 'name' a custom expression so that for a visualisation I've just to insert that name in a custom expression.