What To Do With Ashes?

[TheresaThoma]

A topic over in open mic brought up this question for me. Since I didn't want this to become a free for all I thought it was best to ask it here.
Keep in mind I'm the only Catholic in my immediate family. My mom is agnostic sometimes border line atheist.

When my dad passed away this summer my family decided to have his body cremated for a number of reasons. At the time I was ok with it. I did try to push for burying the ashes but my mom is refusing. She told me that when she dies she would like to be cremated have her ashes mixed with my dad's and then for my sister and I to sprinkle them wherever it is convenient for us though she does have a certain spot she would prefer. This obviously means that in the intervening years my dad's ashes would be sitting in a box on a shelf or somewhere.
My problem is this obviously violates Church teachings and I would be uncomfortable following her wishes. I think I would also be uncomfortable defying her wishes with regards to this. Am I sinning in allowing this to happen? What is my obligation to do and what should I do?

[cappie]

The Church requires that cremated remains of the body be treated and handled with the same respect and dignity given to the corporeal remains of the body. This includes the final disposition of remains. If cremation is chosen as the means of final disposition, the remains are to be buried in the ground of a communal cemetery or entombed in a communal mausoleum or columbarium.

Therefore, cultural practices such as scattering cremated remains, keeping them at home, or interring them at some other location are not considered by the Church to be reverent or appropriate ways of disposition. Whenever possible, appropriate memorialization of the deceased should be utilized at the place of burial.

But there is no sin attached to anything save the disrespectful treating of remains. In your case it is complicated as you are the only Catholic in your family while not ideal your sister and yourself should come to some agreement to best reverently dispose of the remains.