u/Careless-Mistake-55

As you can see from the picture I have some rust on my roof by the opening for the sunroof. Whats the best way to fix this? I want to take off all the rust, treat it with rust converter etc and then paint it again. But I am thinking what if the rust already ate itself through the other side of the sheet metal? Is it possible to have a autobody shop weld in a new sheet on this spot, or will this just make more of a mess than end up fixing the problem?

Thank in advance for all the help!