I've decided to create a handwritting "key." I'm going to find handwritting examples of all of the relatives that I can. I will then be able to compare these samples to different documents. Here are some samples I've already collected:
As you can see, my sources come from many different places: lists, recipes, returned checks and checkbooks, greeting cards and letters, etc. I'm trying to obtain at least two samples from each person, understanding that many people write differently depending on the formality of the documents and for other reasons. Also, I like to try and find a sample of each person's signature. I hope that by collecting these samples now, I'll save myself time and a guessing game in the future.