IMHO, if they have problems, they can figure them out. It is not your responsibility, nor should it be. Just tell them what you want to do, and let them decide what to do about the pix. You are trying to do something nice for the family. Just do the best you can without getting caught up in all the b.s. I am sure your efforts will be appreciated regardless of the details.
What he and other said. There is nothing wrong with being straight forward. If necessary shoot photographs of the MIAs separately and put them in the album. After all, in spite of the hard feelings, the MIAs would be listed in an genealogy.
Warning!! Handling a Hasselblad can be harmful to your financial well being!
Nothing beats a great piece of glass!
I leave the digital work for the urologists and proctologists.