Allow changes to be applied without requiring save Validated

Currently to flatten the fields on a document or make any other important changes to a PDF it requires you to call the Save(Stream) method. I need to be able to apply changes on a document without having to save it off to a stream. There needs to be some type of Apply method that allows the changes to be applied in-memory so that saving out to a file or some other stream is not required.

My current use case: I need to load a page from a file, flatten the fields, and then append the page to the end of another document. I have to flatten the fields before appending because both documents have fields with the same names and I will sometimes need to import the same page (with different values) more than once. To accomplish this today, I have to save to a memory stream after filling the form to flatten them, then create a new PdfLoadedDocument and read the stream back in so the flattened version can be appended to the destination document.