Hello Didry,
Welcome to the forum.
EFT is safe to use with ANY age group. It is very commonly used with; babies for all sorts of physical and emotional issues, with toddlers and all the lovely and interesting developmental issues that can arise and so on.
If there is any issue with using tapping with the very young is around their understanding and permisson. Perhaps if you take a look at the Tapping for all the Family post you will get some more detail on this point. Surrogate tapping for anyone is also an option. You can also read about that on the forum. In a nutshell, if you are working with your own or close child and helping them for the greater good and with the best intention then there's nothing wrong with that.My tip is always tap on yourself first so that you are calm and not serving your intention onto the child's - eg. I want to fix them.
Additionally, it's very important to keep it fun and flexible as it can be possible to put a child off by tapping on them continuously.
Hope that helps a bit, there is so much you can do. Keep in touch
Christine