This is a very concerning issue, and of course a difficult situation for the person who is seeing this happen. As both a parent and a teacher, plus having knowledge of what is now called coercive behaviour , this is very much an abusive situation to me and the child is in a powerless position. If this is the only way they get to see their father, they will be very reluctant to do anything which might result in total lack of contact, so they are between a rock and a hard place. That terrible pit of the stomach feeling when they are travelling to be with the family. Wish to see the father but dreading the hoops they have to go through to do so. It is very much a power issue for the child "eat what I say or you cant be here" So the child has risked telling your friend about it, which was a big step to take and shows trust in the adult. I see this as definitely a cry of HELP and they are desperate to alter the situation in a safe way. So definitely being a good and trusted friend to the child, will make them feel safe about speaking out about this situation. Yes I would keep a written diary and if it is possible to unobtrusively record what the child has to say, so that you are building up a portfolio of incidents over time. Any parent can be forgiven for the one off situation where tempers are frayed for whatever reason, but this is absolute controlling and bullying. If you knew that someone was physically abusing or punishing a child on a regular basis, I am sure it would be obvious that some intervention is needed. In my view this is every bit as bad, or even worse. It is not obvious to others, there are no physical marks to show but my goodness the mental marks are there. If no one does anything this child is left in a dreadful position, where they know that this behaviour is going to continue, they are not able to stop it happening and may fear that it will get worse as time goes on until they are old enough to speak out, but the damage will be done by then. Torturers know that telling someone what you are going to do to them in the future adds to the torture as they have time to worry and become more frightened and feel totally powerless to prevent it happening. So in practical terms , yes have a little stock of food that this child enjoys and can access safely with you (although even saying this , what does it say when you have to hide what and how someone eats?) be prepared to listen to whatever the child says, Stick to whatever promise you make to them, so that they can see that some adults are to be trusted. But I would be inclined to gather some evidence by phone and paper and then contact the NSPCC or social services, where you can show them the evidence you have and give them the opportunity to make contact in a low key way, they should be able to also contact the childs teacher who will be able to tell them any signs they see. e g Every time the child is due to visit the family , they may be withdrawn, be sick or often have stomach ache, which they can say to the teacher as it is a physical condition, but once the background is known you are able to see the mental/physical connections.It is very good that your friend has been able to speak to you and so you will also provide a support when they worry what they should do. But the most important thing is that something is done and quickly. When families change and children have to get used to other new members of the family there is often some sort of power struggle and pecking order. But it is up to the parents to provide a safe space and rules whilst they get to know each other, never to aid and abet behaviours that dont help a family to blend . As a step parent myself, where the age range is quite wide, on the first occasion that my stepdaughter came for easter, I changed my old routine of hiding small eggs in the garden for an easter hunt. Thinking about it I saw that either it would be seen as too babyish, or the older child would find most of the eggs and this would be upsetting for the younger one and a potential danger point. So I bought a selection of very small eggs etc and my husband and I sat for an evening each with a cotton reel. So we wrapped one or two items in cling film, tied it onto the cotton, pulled a good lenght out and repeated this several times. This way I was able to check and recheck that precisely the same amount was on each reel . Then we hid the cotton through toys, welly boots etc etc and up the stairs. In the morning when they both came in we said "Happy Easter" and told them to follow the strings. They really enjoyed winding up the cotton and finding each little gift . They thoroughly enjoyed the fun, could see that they were treated absolutely the same. This is over 30 years ago and they still talk about "the strings " and I have had the happy chance to see my grandchild being given the opportunity to do the same. So a bit of thought and effort really did pay dividends and is now a very happy memory shared by all. Let us hope that some decent and kind adults can provide some pleasant and normal memories in this poor childs future.