VS 2008 Deserializing Part Of A Class

I'm saving potentially very large amounts of data to disk as a single serialized class. But there is a sub class that I would like to be able to retrieve and write back to the disk without having to read the entire file or write back the entire file. Trust me, my reasons for doing this are good, and the design behind this is more than correct.In VB6 this is very easily done. A single statement gets the portion of the data you want from the front of the file and saves it straight to the Type it belongs to, flawlessly. Likewise, if the dimensions of the data haven't changed, but only the values, then Put can be used to save it right back to the file without disturbing the integrity of the entire file.When needed, the entire file is read into a larger structure, and the entire file is put back, but only when necessary. Most of the time the only information being read from and written to the file are in the first few hundred kilobytes of the file.

Now that I've got serialization working, I'm trying to use it to read (deserialize) only the first member of the class serialized to disk. I haven't been able to find any examples of this anywhere that have lead me toward making the sort of progress I'm hoping for.So I suppose the first question is this: Is it possible to read only part of a serialized class from the open file stream? Specifically, in one case I want to read the first two integers stored in the class. In another case I want to read only the first block (sub class) from the open file stream. In both cases I do not want to read the entire file, but just what I'm interested in starting from block 0. I don't need to write back the integers to the first file, but I do need to write back the block to the second.Assuming that the answer to the above is yes. My second question would then be: How is this done? I want to work with the file stream already open rather than opening and closing file streams over and over.I