Element Pairs:

Every time a new element is added or suggested, there is always the question: Will it break saves?

The answer is nearly always yes, followed by a short fix and a roundabout no because the save now exploits an obscurer reaction that almost no one uses.

While this is fine it inadvisably damages things, and I have ended up having to fix some saves because of it.

To solve this, I suggest the idea of adding new elements in pairs with one element being dependent on the other to be created.
When an element has being decided upon, developers should wait to implement it until a second element has been suggested that can be used to create the first.

As long as this is done, we could build upon the game without deconstructing what is already there; new reactions would no longer harm saves.

jacob1:
Most times when saves are broken it's unintentional though:

Intentional or not isn't part of the point. The idea is too create a proceedure for making new elements to ensure that they can't break existing saves, even unintentionaly.

"Can you give examples of what has been broken?" 

Most of my saves that have being broken have being fixed. I've already stated the problems in the official game feedback before, but I'll put them all back together in that section again if you want.
I wouldn't want to fix the problems now anyway. If we did it would break other saves in the process, all the changes I noticed are quite old.