Magento Email Template how to set up correctly?

Question

Magento

Version 1.9 ...
In general, I can’t find a normal solution to the problem.
The store sells fabrics and other small items. The warehouse does not always have what is on sale, so when the buyer buys something, he is sent a letter about a new order, which contains information so that the buyer does not make payment until he receives confirmation of the availability of goods in stock. This message is embedded in the template.
Further, if something is missing, the order is edited, respectively, the first order is automatically canceled and a second one is created, already with up-to-date data. And then you need to send a letter to the buyer that the order has been edited, these things are in stock and you can pay. But the edited order is perceived by the system as a new one and the first letter about the new order is sent to the client again, where the text is sewn in that the client does not pay.
In general, the creation of conditions in the body of the letter suggests itself. I found information that with the help of depend this can be done. But I can't figure out how and to what to attach the condition.

Answer 1

You can write a module in which to intercept the creation of a new order after canceling the old one, according to this condition and substitute another template from transactional letters. Purely theoretical.