A 2 year old still need to have basic needs met – food shelter changing warmth and attention. Depending on the nature of the baby, they might be easy to care for or not depending on whether certain habits and comfort measures have been consistent. The cues from the child will be observable based on how they respond to the new person or CASA – it will require careful observation and asking a lot of questions to the caregivers in order to know if there is certain. food, toys etc that are important. Playing with them with help to see if they interact well and if they appear happy and trusting
A 7 year old is able to communicate and if questions are good a lot of information will probably be forthcoming directly, She will need much more verbal reassurance and explanation- her mind and development can be critically affected by being removed. This might even end up being her most and first impressionable memory ever. Talking while playing a game might be a good idea
A 15 year old also need to be explained everything and the causes – and the future and what to expect next more as they are probably more worried about being far from any and all of the support system (friends and family) they have. I think this age can possibly be more rebellious or deviant but they still need to hear it.