Controlling xmlserializer without explicit order

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C#

XML

I'm working on an issue where we have a class (with tag Serializable) that we need to serialize into XML. We cannot viably set the order on every property because to do so would be a huge refractor. It's writing things out of order from how we expect it in the schema after recent changes. The schema validation blows up when we deserialize it because it's out of order. Is there a way to either set the order in the class without using the serialization order tags (the properties already appear in the order we wanted), or make it so the schema can handle things being out of order without changing the XML version (using sequence for the elements, and it's xml 1.0)?

What I have tried:

setting order on each property (not practical - too many classes inherit, complete refractor) and ignoring deserialization errors (doesn't fix root problem)