Our process most looks like "deliberate sabotage," where we have systematically put little, then big challenges into the mix so that DS learns that he can manage them. This can be as small as buying a different brand of bread, or "running out" of his favorite snack. Even if some of these challenges result in meltdowns, afterward we have debriefed and he is able to agree that yes, he's still alive even though he didn't get X, not getting X did not result in serious harm, and he lived to tell the tale. In the short term this is extremely exhausting, but over time it does yield more resilience.
I do this too. I try and pace these exposures so that he's not too stressed out, but occasionally I'll deliberately
not smooth things over for DS8 so that he just has to DEAL with it. Sometimes he rolls with it, and other times he melts down. I think overall it's helped though.
