What are some good practices for preventing family feuds when it comes to dividing up a relative's belongings when they pass away?

Mom recently moved into an independent living center. Her large house, which has a fair amount of items that have either monetary or sentimental value to family members, will probably be sold within the next year. What belongings she hasn’t taken with her will either be divvied up by family members or sold.

Our parents always felt strongly that items should be divided up evenly. While this is agreed upon by their children, there are some foreseeable challenges in the near future.

1. Out of the four children, there is only one son. He has a son, and I can see him playing the ‘carrying on the name’ card when it comes to selecting certain family heirlooms. He has already taken Dad’s guns, including a Luger Dad brought back from WWII.

2. One of the siblings passed away several years ago. She has three young adult daughters. Mom has addressed in her will that they get ¼th of the monetary share of her estate when she dies. Should they be included in the selection process of divvying up the belongings?

3. I am the only one without children. There are a few family heirlooms that I would like to have, but fear that there may be resistance from the others, even if the SO and I promise to return them to my family upon my death (if anyone wants them).

What tips do you have for preparing for this type of situation? I want to keep this as amicable as possible.