Why piggyback off of GA events?  Why not just send data both to DTM and Google Analytics at the same time as two separate entities (as they are)?  Somewhere in your code you are pushing the GA events, just add onto that part of your code and include pushes to DTM.   

Ideally, you should already have an event based rule or a direct call rule setup for the order confirmation, where all of the data concerning the transaction is readable.  Price point, the list of products, shipping price, whatever...   Assuming you already have such a rule setup this way, you would...

You're trying to push to an Object instead of an Array.Your code should be in this order using an array of objects:- Declare your arrayvar digitalData = {};    digitalData.ecommerce = {};    digitalData.ecommerce.transactionProds = [];- Push to it.var aProduct = {    'sku':'12345',    'name':'Produc...

Are you sure that site.com and mysite.com have the same DTM include?

I would put my money on the issue with e-commerce tracking disappearing having everything to do with your 404 page for the data layer file.  You also mentioned that the URL structure has changed for the order confirmation page.  Without knowing your current DTM setup, we can't really provide a thoro...