There is a model for a schema that will be the result of a data conversion in 2011. Others are undertaking Business as Usual (BAU) changes on the live database. The BAU changes (consist of some relationships) need to be applied to this model. The definition of these relationships are available as SQL. Also available are the access to the database to which they have been applied and reverse engineered.
Reverse engineer the database (new model will be created) and then use Sync & Convert wizard with action Model Merge. (Model update can be used as long as SCHEMA specifications are identical in model and database).
Enhancement request ST75147 has been submitted to Development for consideration in a future release of Toad Data Modeler.