With both people, I've tried, to no avail and with increasingly bad results. I know that one on one is the way to go, in a matter-of-fact manner, not too pushy, not expecting big emotion and not purporting to know how they feel already. Giving concrete observation of behaviour that leads me to believe there is a problem and matter of factly stating care for and offering a listening ear to the person in question is good. Allowing for more silent time or even an interval of time with ISTJs is also useful. Not expecting to see immediate reaction to my words on the STJ's face is important as is realizing that they are not intentionally trying to be hurtful. Perhaps explaining the common pitfalls in the two communication styles in layman's terms so that they have an idea of how to prepare may be of help (This I haven't tried, because until now I wasn't sure enough of where they were coming from). Does that sound like a reasonable summary? Have I missed anything or misunderstood anything so far? Then an almost blunt assessment of the situation as I see it?
I also wondered, if someone can accurately guess what the STJ is feeling and states that (in an appropriate manner), will the STJ feel vulnerable and unfairly exposed and layer up even more?
For us, feeling understood by someone is the biggest comfort and compliment one could give. Even the desire to understand us is a huge help (and this can be done asking concrete questions). I too am careful about revealing too much lest it be stomped on, yet my need for intimacy (top of the needs list for NFs, towards the bottom for STJs) compells me to. Therefore, when it does get stomped on (even unknowingly), there are larger and larger chunks of me that you'll never see and yet I'll wish that you wanted to. Because you have less information, you'll also have less context for figuring out my behaviour, which makes you antsy when it starts impacting you negatively.
Amira - That's a very accurate assessment of it. I think that you are right that the STJ would still feel burdened by all the little problems and the NF just couldn't go off on their own and deal with it (maybe they could to handle more things in stride, but not everything.) It's funny you should say about some people feeling conflict brings them closer. I do not fly off the handle easily, but on one occasion I did with someone older than me that I worked with and who had pushed their luck in every way possible. I ended up telling him what I thought, he ended up giving more context and showing how badly he felt, we came to some agreement for how we could work together better in the future and things have gone swimmingly since, with great mutual respect. I don't like drama in my life but I also realize that compared to the way STJs naturally function, I would still be considered oversensitive.
I'm also really glad that you wrote out how you would see the most comfortable way to handle things as being. I need to mull...
An interesting thread that one ENTJ just started is called "The iceman and the child". I wonder if it will bring further answers...
I really appreciate everyone's participation and patience in getting this thing figured out. How lucky are we???