I think you need to climbdown, you are massively exaggerating what has actually happened to the point of almost being hysterical.
The door went (not BANGED! OP never said banged), the door was shut in their face.
The next the door went again but a different person (NOT BANGED!), the door was shut in their face.
Today they have arrived together, there is absolutely NO evidence that they hid and waited for her husband to leave, the door went and there was two of them, it was shut in their face, they decided to stay on the driveway.
Staying on the driveway seems extreme, but without knowing why they were actually there and why they feel it is so important to talk to OP in person, no one can really judge them for thinking that it is the best course of action, they should have left when DH asked them to but they obviously felt if they waited OP would communicate with them, or what they had to say was so important as to risk the police becoming involved.
OP FINALLY, as advised by many, many people on this thread communicated with them that she knew who they were, but didn't wish to talk to them about anything related to her family.. and they then left without fanfare.
Which begs the question, if she would have just acknowledged their presence and sent them away instead of completely ignoring them whether they would have even bothered to come back in the first place.
No one has been "stalked", no one has been "threatened", no one has been "harassed".. OP is scared because she has a very complex past family history that is extremely raw.. but these people aren't responsible for her pain because she didn't even know they existed until last year when they emailed her, they are just a reminder of that which has caused a physical reaction in her, but they have no clue about that because they don't know her and she refused to say anything to them.
You really are dramatising events @TheGentleOpalMember