What to do about my stepdad and my mom's ashes

My mom passed away in early February. For a multitude of reasons I do not like my stepdad, and now that my mom is gone, I'm really only trying to interact with him when I see my siblings.

My mother was cremated as per her wishes. I knew that it would take some time for the ashes to be shipped, but I never actually heard from my stepdad that they had been sent back to him, I had to ask my grandma (my mom's mom) to even confirm that we had gotten them. It's been almost 4 months and he has not mentioned them to me once, let alone split up the ashes for family members. I do not have any ashes and neither does my grandma.

I was at their house a while ago to visit my sister, and I didn't even see an urn or anything like that. I think it would be one thing to not split them up yet but I don't even know where the ashes are. Many other things have not been done, for example an obituary was written but I don't think it was ever published anywhere. We're going to do a celebration of life but it's not until July.

At this point I'm not sure what to do. I feel like I shouldn't have to beg my stepdad just for some of my mom's ashes, and I honestly just don't want to hear whatever excuses he will tell me about why they're not even in an urn and why they haven't been split up. This is also partially a vent, but any advice about where to go from here would be appreciated.

(Standard I'm on mobile, if I don't reply it's because I'm at work, and so on)