[Update] My sister wants to use a burial plot that she doesn’t own

So - the short backstory, my sister is a bitch who is holding my mother’s remains hostage to get her way. She wants to bury my mother in the plot I own that I buried my father in. They have been divorced for more than 40 years.

The update, after some research I offered to pay to inter my mother in the veteran wall. My sister through a fit. Not directly to me, we don’t talk. She just let the funeral home know she wouldn’t return the remains. I would have to buy a few plot, but I just bought a house and I am furnishing it so money it tight. She knew that. It was Mom’s house and she is mad I bought it. She has driven by it several times. I am about to put it out on the short term rental market.

So, after talking to my family, the grandchildren and others, I have thrown in the towel. We are burying Mom in Dad’s plot. She will have an I ground brass marker. It kills me that my Sister has reduced my Mom’s service to a brass welcome mat to my Father’s headstone. My family has said they will know but damn it hurts. My Sister cannot take some money from the sale of the house and buy a plot or split the cost with me.