This is really cool, about using family reference samples, or samples from toothbrush of the missing person or similar. The idea is to have databases of all the unidentified remains that get collected over the years and all the DNA samples for identifying the missing people, and over time, you figure out who all the remains are and the family of the missing person at least gets some information.
There's been some publicity in Massachusetts about children already being watched by child services dying, and there was a NYT article about children in foster care/ward of the state/group home situations in Chicago going missing. Predictably, law governing inter-agency cooperation can become an issue.
Reconnecting runaways and/or lost children with their families is obviously a universal problem, and can be particularly difficult when the child doesn't know where there home is/was because they left it at a very young age. But modern technology and good procedures can help.