When I was with the support groups based in overseas, we often shared our heartfelt talks about ‘visitations’. Of course, the group has moderators who normally try to point out the facts so as not to confused the newly bereaved parents.
When a parent is newly bereaved, some may be so deeply in grief that they lost their normal way of reasonings. One mother whose daughter committed suicide after a few months in her university, was waiting for her daugther to return every day. (after the death) She would sit and wait in the dark for her return.
I was related to the family and advised her children (two grown adults) to continue reminding the mom that their sister is no longer coming back. Though it may seems cruel, it has to be affirmed into her what is fact or otherwise, she would sink further and further into her confusion. Though I did get some contacts for the mom to seek a counsellor, the family was not receptive to the idea. (she is much better now)

So, although bereaved parents do really want to be ‘in touch’ with the deceased child, it is often good for the people around to gently remind the bereaved parents of the reality. Do not encourage the bereaved parents to dwell too deeply into any sort of beliefs, rituals or shamans where they can actually get in touch with the child. However, it is also very hard to stop the bereaved parents as they are very focused on doing whatever they believe in.
Like my relative, she went through a lot of agonies in trying to appease her daugther. Mediums in trances told her that the soul was left behind in the university in another state, 600 KM away. She went to great lengths to bring her back. The airline did not allow her to bring the umbrella (which is purportedly to shelter the soul) into the plane. Hence, she was so stressed out that her daughter had failed to ride on the plane with her to return. Thereafter, she went to even more rituals.
I did not want to be involve in their family affairs after giving them the counsellor’s contact as we were of different religious faiths. A kind word from me may receive hostile reactions. I only observe from far.

As for me, I did went through some situations where I truly believed that there is some form of subtle messages sent to me. I shall elaborate more on another post.
For the parting message, if you are a bereaved parent, allow yourself just some tiny signs and subtle messages. A butterfly. Some feather. Or flowers that bloom mysteriously. A dream, maybe. Whatever it is, do let your child’s soul free. Do not hang on and try to call him/her back. This will only make everyone’s life much more difficult. With time, you will have less need to be ‘in touch’ because you know that your child is safely up in Heaven (or any place that your religion believe in) and you will slowly meander back to life here.