ISerializable and DataContract

Using WCF In Silverlight services, typically we want to use the DataContract and Datamember attributes to opt into what we want to have serialized. This is what we send to and from the client. For most things this has never been a problem.

However, I have a few classes I am trying to s开发者_开发技巧hare with my silverlight app, 'mature' classes, that I would like to send to the client full of data. These classes implement ISerializable which, doesn't like to play nice with the WCF service when I update.

I need to leave the ISerializable attribute on there because it is being used else where is some older code. Currently the way I see it is my best option being to have a new class to transfer the data through, if at all possible I would prefer not to have to write a class just for transfering the data but I am thinking that is what I am going to have to do.

Any Ideas on what I could do to get this to serialize through a service and still be able to keep the ISerializable tag on there?