(ncc Delaware) Sister Is Addicted To Fent, Lives With My Mom With Her 3 Kids, Things Are Escalating.

To get started we are located in New Castle County Delaware, my sister 39, the kids are 17, 13, 7, my mom is 64 and on disability, my sister has not been able to hold a job and my sisters ex-husband is a deadbeat too.

A little backstory

My Sister:
She left her husband in which she had the three kids with to chase after a different man, and my mom and sister never got along. My sister and her three kids moved in with my mom at her 2 bed / 1 bath ranch back in 2020, I kicked her out in 2021 after abusing my mom mentally and physically and she willingly left. She went into a shelter with the kids refusing any communication between my mom and her grandkids, she refuses to let my mom be their guardian, she would rather drag them through the mud too, pretty selfish IMO. Fast forward to the end of 2021 my mom found out she was in a shelter (and against all of my wishes and begging) let her move back in with her 3 kids.

The Father:
Refuses to pay child court mandated child support, takes the kids 2 weekends a month. The kids are fed junk food but are fed, the house he stays in is covered and dog waste and pee, and he has a bird that attacks the 7yo.

My Mom:
Does it for her grandkids. She is on disability so a very fixed income, no retirement savings, a house to pay taxes on and utilities. I have been paying the Delmarva Power bill and half the taxes for the property for her as all of my moms money goes to feeding the three kids and buying school supplies and clothes. My mom does frequent multiple food banks to assist with feeding the kids. My mom is 64yo about 120 lbs and fragile after many different surgeries and cant fight back so she can't defend herself if needed against my sister.

I have been trying to tell my mom that my sister has been using something for the last 2 years but she was in denial until my sister on 12/12 started begging my mom who is on a very fixed income for money. When my mom doubled down on NO my sister confessed to being addicted to fent and that she was sick and going through withdrawal, the answer was still no. From my understanding her boyfriend who also has no job picked her up and took her to New Castle to get Methadone treatment, which isn't helping.

Sunday 12/16 10pm
I get woken up by my mom calling me twice to override the DnD mode on my phone. I could hear my sister in the background throwing a fit begging for money, that's when I found out that my sister assaulted my mom in my moms car the same day because my mom wouldn't buy her cigarettes. I hang up and call the NCC Police and they have someone over within 5 minutes, by this point she had locked herself in the basement room.

This is where I need help:

The cops that came out said that without an active crime being committed there was nothing they could do. The officer also informed us that even though she had no rental agreement with my mom and because she has been there for almost 2.5 years we would have to go through the NCC court system to start eviction. We tried this 6 months ago, we even had hired someone to serve her and had sent certified mail the notice. She dodged BOTH of those services and I physically handed to her the eviction notice. We went to court and the judge said that there was nothing they could do! That it was a civil matter! WTH! I was so frustrated at this point.

What needs to be done so my mom can gain custody of the kids and get my sister out of her house and hopefully into a recovery program that is inpatient? She is killing my mom mentally, physically, and financially and although my mom locks her door at night now, (I installed a keyed lock and will be installing a deadbolt today) I don't feel she is safe.