Along with the letter informing you to get the medcals done, cic would have inckuded a medical form. These fprms have section A to E. The applicants have to fill (if it is not already pre-printed), section A only. the dmp would fill out the rest . Use this guide to find out which dmp is closest to you www.cic.gc.ca/dmp-md/medical.aspx
Call the number for the dmp you have selected and then make an appointment. Ask all your questions as to what your parents need to take with them, if they can have breakfsast, costs', number of pictures etc. The address where the results must be submitted would be mentioned in your letter. most likely, it would be an Ottawa address. Since this is a new process and dmps usually send the results to local address, clarify on the phone where they would send the reports. ask for the option to send the report thru a courier and see if they can give you a tracking number - they might charge extra, but you would have peace of mind.
Lastly, if your parents are taking any medications, take those medicines along with the prescriptions along with them.
Everything should turn out just fine.All the best.
Thank you so much sakamath for give me this information.