@sparklins adult children of alcoholics are usually people who have never had boundaries respected and while it's good to see you are strengthening yours, I really, really recommend you get professional support if you don't currently have a counselor. The problem with feeling you are doing better is that you don't have a baseline/ appreciation of what's normal against which to measure your progress. Al Anon for families is an excellent support.
DM - once I made it clear that DBs boundaries cant be invalidated just because she feels like they are not good enough she kind of doubled down and started saying how our DGPs have felt about his recent interactions with him and how they are ''upset'' and ''sad'' about the way he spoke about something and she was saying things like ''how are they supposed to feel'' about his alleged behavior. Again this was about something she took completely out of context and DGPs have most certainly not been upset as again I am in regular contact with them and we have talked about this situation extensively.
Not sure what she was trying to achieve by saying that and trying to play on my feelings.
Trying to make topics such as boundaries and other people's reality clear to active alcoholics is a complete waste of your time. You feel you must, and that is why you need professional support here, or Al Anon, or both. You need to learn to let them be, to stop engaging, to stop trying to get through to them.
They are alcoholics. What that means is that other people are not real to them. Alcoholism renders its victims profoundly selfish, profoundly unable to see anyone else as a real person. All they care about is protecting their own drinking. There is no relationship with anything but the booze. Reminders that you and your brother are real and deserving of respect and love will be batted away because those reminders are a threat to the drinking.
You can't let them get into your head as you have done here for any reason - be it curiosity, a desire to give your rational brain evidence to form a conclusion about their behaviour, whatever.
Do not engage with them while they are drunk. As long as you are willing to do this for any reason, you are allowing them to breach your boundaries. Just the mere fact of them picking up the phone and dialing your number while drunk shows how little respect they have for you. Do not let them get away with this.
As soon as you realise they've been drinking, tell them you're going to hang up because they're drunk.
Do not engage with them if they are sober either (whatever that means for an alcoholic) if their conversation involves your brother or other relatives. Triangulation is unhealthy, even if you are fighting DB's corner. Tell them you are not going to discuss your brother or anyone else with them. Stick to your guns.
They will try to drag you into dramas so that you will bolster their agenda, which is that they are normal, there is nothing amiss with them, everyone who says there is and that they have mistreated them is wrong, and sparklins agrees with us, so there.