You can't do this. This seems like a good idea, but it's not, and you need to find a solution that doesn't involve breaking DNS to suit your needs.
We've been getting variants of this question several times in the past year.
The answer is pretty simple here: you can't do this. Any software that lets you define or otherwise synthesize multiple SOA records in this context is broken software, and doing broken things is not on topic for ServerFault. You either need to choose DNS software that makes this management simpler for you, or you need to come up with a different strategy that does not involve this particular shortcut.
There are definitely some tricks you can use to make life easier...using BIND as an example, it's fairly commonplace to define multiple zones that all reference the same template zone file. This is perfectly legal and validation software will find nothing wrong with it. Most people pass over this solution because it's still "too much work", because you still have to add a new zone definition every time.
Newer versions of BIND support an option called allow-new-zones that will let you dynamically create zone definitions on the fly via the new rndc addzone functionality. You might want to take a look at this and see if it fits your needs. Other than that, we're sorry, but we can't help you with a solution to this particular problem. Sometimes you just have to do things the hard way, even if it would be theoretically possible for the software to save you the trouble.