I have been on both ends of this so I have NC to comment.
My father has multiple children with multiple women so I have a lot of half siblings scattered around. I as do they all have a terrible relationship with him.
Occasionally they would contact me, and I would genuinely freak out. I would associate them with the horrible childhood he gave me. I just saw them as an extension of him and it used to make me panic. I would ignore the messages and hope they would go away.
They didn’t bother contacting me again after a few tries and now looking back I do feel guilty. His behaviour was nothing to do with them and they just wanted a relationship with their half sibling.
Fast forward to around a decade later everyone I know was doing an ancestry dna, so I did one too. Not to find family just to see where I was from. I matched up with a sibling I didn’t know I had and contacted her, and she had the same reaction I had when I was previously contacted by my half siblings. She said it was a lot to process and she didn’t know what to make of it/ if she wanted any contact and never messaged again, so I didn’t either. (all fine, she’s well in her right to be overwhelmed by it and not want to relive the past, I totally get it as I was on the receiving end of it once too)
What they’re doing lingering around the drive way and knocking is very intrusive and I can understand why you panicked. I don’t think the police will do anything. Try and pluck up the courage to say you are finding this too much, and please don’t return, you will contact them if you wish to in the future. Ask your husband to if you can’t.
Breathe! It will be ok. You’re in fight or flight mode. I’m sure they mean no harm and are just excited they found they had a relation to you. But have gone about it the wrong way. X