I know that your BM is terrible and that you're really just tyring to make things better, but you need to back off.  What she's doing is awful, but trying to guilt trip her into co-parenting isn't going to help, and giving her facts and figures only makes you look like a sanctimonious jerk.  They're all true, yes, but she doesn't care.  Pushing her to the point that she gets angry and says something rude will not help the situation.  Any "documentation" you get from that is easily explained away.  She will say that you and DH were teaming up and harassing her (which won't look good for you in her pro-BM state).

You need to take a BIG step back and your DH needs to be dealing with the situation.  Yes, you're a team, and you want to support your DH and SS, but you are not helping the situation.  Suspend the cell phone.  Send cards and letters to SS, etc.  Your DH is entitled to a relationship with his kid, but he's 14 and screwed up.  The solution to that is not to engage with/lock horns with BM.  

  I would not send it…I would let DH send it though.  She obviously does not want to talk to you or co-parent with you or DH, but anything that you may want to use in court, should really come from DH.  She will just claim you are overstepping and harassing her.  (She is a loon)

I would also take out the list.  I would just tell her to look up the issues that kids have when mothers will not let the father be involved in the childs life. 

Is there any way you all can move to where SS lives?  I forget why yall live so far apart.  SS is going to be a lost cause if he is not around your DH more because SSs mama is going to ruin him.  She is just a horrible mother. 

It's not going to make you best buds co-parenting happily ever after. 

She has clearly wrote off any chance of Dad and his son seeing each during this next visit to her trip. Sucks, yes. But do you really think trying to shame her is going to help in any way of getting her to change her mind? 

If she were a reasonable parent who sincerely desired to forge a relationship between father and son, she wouldn't be playing this f-off game in the first place. Yes, she told a judge it'd be no problem if Dad came to her state...she lied. But as long as the court order still only gives dad x and x she is under no legal obligation to give Dad each time he contacts her and says he is coming to her area. Yes, she's being a butt, however throwing rocks at her via text/email isn't ,, IMO, going to change her mind. But it will anger her.

Ok, so this upcoming trip didn't 'work' for her , instead of nailing her on being a rotten selfish parent, maybe try writing that Dad is extremely disappointed but would like to schedule another trip now that he would be available and before something else on her end is scheduled. 

The more times he tries to schedule and is rejected, the better her silly statement in court about of course, she'd never deny Dad if he was in their state will prove it self bull. She won't be able to go to court and keep using that lie. 

I think you should remove yourself from addressing this issue and leave it alone. It seems like you have good intentions and only want the best for everyone involved but this has to come from your H. I find that when you address someone and trying to persuade them into something that you have to remove the negatives in the statements that you make. Don't make this about you, your H, how good your Ex was or potential "daddy issues" because that could easily piss her off. Your H can say something to the effect of:

"Hi BM, I know you're a caring and loving mom and I would like nothing more than to coparent with you and make this transition with our son as smooth as possible given the circumstances. I know we've had our differences but I believe with good communication you and I can come to an agreement and be on the same page when it comes to our child. I ask that you please reconsider me seeing our son. As I love and miss him very much and want him to know that he is loved by us both and want nothing but the best for him."

You know the old saying "you get more bees with honey". Whether your H means it or not is on him but the goal is for him to get to see his son and he's pretty much at her mercy so he should take a different route and address her in a more positive note.

I think you need to let DH with this.  Putting it in writitng that you think she should she be co-parenting with "US" is a mistake, at least where I live.   YOU do not have legal rights.  Now, as a practical matter, you may be sharing pareting with DH, but where I live, the courts/guardian would blast you for this.  Comparing herself to you in an unfavorable light is not likely to win friends and influence people.  

Just because normal people might appreciate your letter, which is really nice (but do not send!), doesn't mean a BM will. I am a peacemaker & would appreciate a caring, non-hostile communication like that to keep my priorities straight, but I suspect your letter would be the "excuse" she needs to twistedly justify her sick PAS and withholding visitation, and probably reply with a rager. In saying, Don't Send, I mean it in terms of self protection - NOT that it isn't a nice letter. 

I wouldn't send it.  Maybe DH could send it, but I doubt it will do any good.

If BM suddenly changed her mind and decided to let SS visit with your DH more frequently, would he still be going to Japan?  Does he have any say over what his orders are?  Because frankly, if he's going overseas within the year, it really doesn't seem to be worth the time or effort to fight for more visitation within the next few months, especially for a 14 year old who most likely is already brainwashed and who lives in a state where the courts are clearly not doing him any favors.  By the time you get back, he'll be an adult or close to it, and can make his own choices regarding seeing his father.  

It won't work. It will make matters worse, so don't send. Nobody likes to be put on the back foot. She will immediately be defensive. This letter won't make her see the error of her ways.

If you feel you must send something - say something like you said in the text, talk about what a great opportunity this would be to see DH and say you feel sad that things seem to have deteriorated since your talk in May - ask if there was anything you did to make it worse and if there is anything you can do now to help fix it, particularly since you all miss him. 

I know that's bullshit. But the goal is to 1) let DH see the kid and 2) document for court. 

Don't send it! This letter is full of accusations and all about your feelings. It will only cause a fight and further alienation.  If you must, reach out with a friendly follow up reminder letter letting her know that you're there for her and to contact you if she needs anything.  

Read up about "Writing Postively."  You can convey your point using positive supportive language that will look great in court rather than look like you're attacking BM.  

I think you should back off. Also letter is very accusatory. Don’t send it. Co parenting with “us” doesn’t even make sense as you are not the parent of SS.

Saying that, BM is terrible but you can’t fix it by sending accusatory letters talking about yourself and how you do things right and how she does them wrong. Bad idea