***First post alert*** My 12yo SS and his BM moved from another state a little less than a year ago to be closer. This is a decision that BM decided on her own without much conversation with us prior to the move. She also decided where she would live which is walking distance from my DH and I. Overall we don't have a bad relationship but it could definitely be better. Throughout this past year we have been trying to  adjust to the changes while trying to do our best to keep the peace. My DH and I have been together for going on 6 years and married for almost 2 years. For the first 5 years we have had 7 hours separating us and only needed to communicate for exchanges, issues with school etc. So being walking distance from each other has been a lot to deal with because we have never had to address boundaries because we simply did not live close. 

So now that we are living around the corner from each I feel like there is a major issue with boundaries and they need to be addressed. BM has dropped off SS on one occasion at a random time in the morning. She has also recently come to our home and asked to speak with my DH in which I promptly let her know that she needs to let one of us know before she just shows up and that turned into yelling and her saying I needed to stay in my place.  Keep in mind her son was NOT at our house at the moment. She was upset that my DH had not answered a text fast enough so she came over. It was minutes in between the time he didn't respond and she came over. 

We have SS every other weekend. And we put him on the bus for school on Monday morning. This past Sunday BM simply asked SS if he had his things together and if he was ready for school. SS said he needed to wash clothes. BM then said she would bring him clothes. This entire conversation took place on SS iPad. DH was busy washing clothing and was unaware of the conversation. SS simply went to the door without telling DH anything  when BM came and she brought him the clothes. A short time later, after she had already dropped off clothes, SS and BM were discussing her coming back that night to bring his medicine he had forgotten but THEY opted to wait until the morning. 

A few things to note:
1. I am aware my DH needs to be more proactive about making sure SS has all his things for school so that BM doesn't feel the need to have to and I have spoken to him about this fact. 
2. There is no order in place for custody or visitation 

3. I do believe that the reason SS goes to BM for the things he needs is because he has spent the last 5 years depending on her for things because of our distance so I realize it's hard for him as well. 

I need to know what is the best way to address this situation. Thus far DH asked BM again to let him know before she comes over and she simply said ok. Would it be wrong to have DH talk to SS about making sure to notify the adults of the house BEFORE BM comes over. Or if he needs anything to let us know. (Note: DH has previously talked to SS about letting him know if he needs anything).  I don't want him to feel like he can't talk to his mom or that it's necessarily an issue about him. Or even that we're mad at him for anything.  But how do we address the need for him to not just have BM come over without telling us first. Its also very obvious that BM feels like she has the right to come over at any time whether SS is there or not so long as she is bringing SS something or even wants to discuss SS with DH.  We do not have that kind of relationship. I wanted to be that comfortable but the fact is I'm not ok with her just showing up nor does my DH. Am I being unreasonable for not being ok with this and not being ok with a child just walking over to my front door and opening it for someone and I have no clue who it is?

This also creates a lot of tension between myself and my DH because he has repeatedly said "what do u want me to do if she/they keep doing it?" when I bring up boundaries. He's tired of hearing me talk about it and tired of BM crossing boundaries that would seem to be common sense and I'm tired of bringing it up. This is something they have never done before in the past. Am I wrong for feeling like something has to change? Who should be addressed if this happens again after we have asked to be informed? I desperately wish this situation wasn't the way it is. It doesn't have to be this hard but it is and I hate it. I feel like I'm picking but if I don't say anything I feel like I am a prisoner in my own home because regardless of who it is I am not ok with ANYONE just showing up at my home without my knowledge. 

Thanx in advance for the feedback