I have been using ptc cad for 20 years and I would not recomend that anyone ever use this pieces feature. The thing took 3 tries to regenerate and gave nothing you wouldnt have got if you had just selected the edges.
I have had years of trouble in sending cad files from ptc pro engineer, wildfire and creo to a toolmaker or mouldmaker. their programs cannot read a poor model.
Keep it simple. DO NOT LET CREO ASSUME ANYTHING, TIE IT DOWN YOURSELF.