Animal cruelty please help!?

Some family friends have 2 pit bulls. A male and female the female was pregnate and had babies. The female pit bull lives behind a truck in the trunk with her puppies and theirs a dog house also, all in a small trunk. the mom is tied up..problem is SHES ALL BONES. like she's soooo skinny (i took some pictures for evidence). I asked some teenager "why is she so skinny" and he said bacause kayla doesn't feed her (kayla is his sister in law). I mean she has kibbles thrown all over the trunk (not much though) but she does not seem to eat them. My brother gave her some food and she imediately ate it. Im not sure if they have water. I want to call animal services but im afraid it will cause problems between our families. I am only 16 and care a lot about animal. Do u think this is enough for the services to take away their dogs? Can they also get involved with the family if they dont have papers (like being legal) or take their kids away? Aw maybe im over reacting. I know i can call anonymous but im sure the family will know it was me who called cuz i was showing concern about the dog. They said "shes just skinny because she's feeding the puppies" but shes so skinny not even healthy! I will post the pict in a few minutes. WHAT SHOULD I DO?