AGOL Attribute Expressions - allow renumbering

[IBWadmin]

I formatted a custom attribute display in HTML for my popup. Three of the fields in the popup are from an attribute expression. They are not directly from the attribute table.

The HTML for the popup requires that references to attribute expressions be hard coded. For example, 

<tr>
<th>AREA m²</th>
<td >{expression/expr0}</td>
</tr>

That's the starting point for this idea:

Now, deleting the first expression, the other two are left:
(Why I'm deleting it is because the expression gets corrupted after overwriting the service......)

Finally, I want to re-add the first expression, or at least have an expression with id 0 {expression/expr0}.
But, when I add a new expression now, it's numbered 3:

Now I need to go re-edit my HTML in the custom attribute display to reference expr3, instead of expr0. Not convenient in a production environment. IDEA: Allow renumbering of expressions so users don't need to update all other references to a new expression. Let me renumber expr3 to expr0.