I wrote this in an immigration thread but realized the message has to go wider than the NNth page of a flame war.
If you see a beggar holding a baby/child, CALL THE GARDA on the bast**d. It's not even about immigration, it's child abuse. The child is in grave danger, might be drugged, might be sold, and imoact on development is practically assured. Child protection has to step in and as far as I understand, the only way for a civilian-from-the-street to involve it is via the Gardaí.
Whatever one thinks of beggars in general, immigrants, Roma, the EU and a host of other issues is not important compared to this. I would advise against rants on the Garda call - make it short and to the point "a beggar is holding an child and I believe the child is in danger".
DISCLAIMER: I am not a lawyer and this is perosnal opinion (but very strongly held).