I agree with Raven on the CPYF option for appending the data. What is the reason for doing the restore? If the file was damaged or there was another issues you may still risk missing data due to the cap in when the files was backed up till the problem was noticed. You may also possibly loading duplicate records in the case of unique records with changing timestamps. This may even cause for headaches for you. More details on what happened and why you are choosing this recovery method.