Bit of background info, my NDN isn't NT, she has alot of learning disabilities and has a physically disable 1YO DD but also a NT 4YO who is a nightmare.
We get on, I have helped her out with furniture and other household items which I have no complaints about as she is by her own words living on the breadline.
Recently she has started ringing my door bell every single day because DD4 wants to come and play with my DD6, I have had her over once and I couldn't handle it.
She put a plug in the sink and left the taps running.
Drew all over DDs reading book for school.
Swears like a trooper.
Throws things around.
Tantrums and so on.
I said to her mum I wouldn't be able to do it again, it was too much for me as I can't run around keeping an eye on her as I'm almost bedbound from PGP.
She won't stop though, I've had to start ignoring the door because her DD just runs in and upstairs then hides and the mum just laughs!
I really want to stay on good terms as apart from this she is a lovely neighbour but I don't know how to handle it in a nice way.
I'm due in August and I'm dreading the thought of this still happening when I have a newborn 
How can I nicely handle this situation?