what is a good approach, attitude with ghosts, paranormal stuff and children?

the children are from the age of 5 to12, several of these are more or less open. we have gone from the saying i don't see it (any ghost) to "there is nothing to be afraid of", one "entity" or what it now is have they nicknamed "Darky". They do not go where they "know" Darky is. Sometimes I think this is real to them and sometimes they give themselves a fright over nothing. I have been given great advice on how to raise my energy, stay positive, is there something I can in a subtle way introduce to kids without frightening about Darky or any other paranormal stuff they are picking up on?

Anyone else who has been through this who knows...?

I would really appreciate your help :)