My very dear Chloe,
Thank you very much for your kind letter, I am very, very sorry it took such a long time to reply, perhaps you heard I got a stroke and so forth.
I want to say in regards to your question, it is very good to do anything that helps other people, but if it harms people, then do not do it. If it helps others, then it can go with Buddhism. If it harms, then it doesn’t go with Buddhism.
So don’t worry at all. If it helps by telling people about their past or future, then tell the person, but it has to be at the right time. If it will harm someone to tell them, then you don’t need to tell them, even if you know.
Yes, many people may have a future bad rebirth, but to tell them something about that can be very inspiring, so that the person can put effort in practice, morality etc, so they can have a good rebirth and don’t have to be reborn in the lower realms. Just telling them they will have a bad rebirth without telling them that they can change the karma, would just worry the other person, unless the other person really wants to be reborn in a lower realm, as a spider, butterfly or snake. Of course, sometimes people like to be reborn in the lower realms due to ignorance, and also some people, like bodhisattvas, want to be reborn in the lower realms in order to benefit sentient beings. They can take different births in the lower realms to benefit others, so that’s different.
So you can tell others about those things that you see, as long as it is very true, otherwise maybe it’s better not to tell, as they might get the wrong answer.
Also you can use examples of their current life—why it is like this; this is due to past life karma created etc. So then it’s OK to show, like that, but the main thing is to use it so people can benefit, so they can practice more, do purification etc.
Please make your life most meaningful with the thought of bodhicitta.
With much love and prayers...