I'm not sure if I am reading this correctly but I think you are asking about coping skills for the support person as opposed to the individual suffering from the ill mental health.

I think it would be fair to say that you take a page from their own book of coping skills and even use them yourself. I mean I assume it is stressful for yourself and you have a touch of your own anxiety. Perhaps try the 'Five Senses' approach to coping with this stress and anxiety. A 'Cognative Distorion Worksheet' may be helpful to you too in terms of mapping out your own feelings and making a plan.

I appreciate the fact that my own support people don't dig for information. Sometimes it is their silence that helps. BUT, I also appreciate their availability should I want to communicate. I think there is responsibility on the individual to communicate to their support persons just what does trigger them.

I do like it though when my support people check in with me. We have set up some code words for me to use when I need to communicate if I am having a difficult time.