Let say I create a document type called compositeExample with fields A and B. and then create a base document type called baseExample, this is great and I can update fields A and B on any node that is created from the baseExample document type.

Now the problem is, if I update the compositeExample DT, for example add a new field called C, this does not get published onto any baseExample nodes unless I first remove compositeExample as a composite and then re-add it. The problem with this is, removing a composite will also lose any data attached to the fields, so when it is re-added, add data will be reset back to empty.