SAS Model Input variable has changed how to keep model running without redevloping

[SASUserABC]

I've inherited a SAS EM decision tree model, dont have the original EM project just the scoring script.

One input variable has changed values and is used to create branches and final model scores. Specifically the values have changed from a 6 digit code to a 4 digit code with no mapping from new to old.

Is there a way to adjust / re-calibrate the existing model without having to redevelop in SAS EM.

The old input variable had values like "A12C", "B23D", "C34E" and now has changed to "U9", "F2", "H4"...

The old values had greater granuality so two branches could have been split on "A12C" and "A12D" but the new values would be "A1" so no way to determine which branch in the tree it should go.

Is there a way to remove the input variable from the model and re-calibrate the final model scores to reflect the removal of the variable?

Thanks in advance