Mom’s cousin died, no immediate family

I’m not sure what to do. She never married or had kids, and her brother is getting frail and may not be able to sit shiva and pray for her. I wasn’t close to her, but it breaks my heart thinking of her not being prayed over. I want to say the kaddish for her, even though it’s not traditional for first cousins once removed to do that. I know it’s not traditional, but she was my mom’s favorite cousin.