This is a tough situation. Your aunt needs some time to grieve, as you accurately stated.
Is there someone who can advocate for her to work out a time frame that will be agreeable for her and her children? It might be you or another family member or even a family friend. You might also consider a minister, doctor or even attorney, but it's important that her children have respect for that person or they won't pay any attention.
As a funeral director, I hear about situations like this, but you might want to consult a professional counselor, grief therapist, or attorney to explore other options. Your aunt is fortunate to have you in her corner.