Assuming you just have a simple picture viewer/editor (and not something more powerful like Adobe Photoshop), here's what I'd do:
*Open the ID photo and do a save as (to keep your original untouched, because the next steps are going to involve some intermediate editing)
*select the "crop" function and crop it so only the picture is showing
*go to image size and take note of the size of the picture
*exit without saving changes
*now open up your dd's picture and resize it to match the size of the picture on the ID and do a save as so you have both the original and resized picture
*do a select all and copy the resized picture
*open up the unaltered ID image
*paste your dd's picture and move it to cover up the original picture - if all goes well, it should be just the right size.
*then do a save as and print it
Let me know if any of that doesn't make sense or you have problems finding the right menu options - if you tell me the particular program you are using, then if I have it I can start it up and run through the steps myself to see just exactly which options to use.
HTH