I think it's possible they are moving girls around the country, to prevent inbreeding.  What troubles me is it seems the Ofrenda has been happening pretty regularly (sounds like once a year?) with girls being sent out of the town to wherever it is they are being sent.  But the town has not received girls (or young men, if the numbers are skewed such that they need more young men -- I can't really tell, tbh) from the Ofrenda, just keeps sending girls out.


So what is the point?  To keep rich old men supplied with pretty young girls from the provinces because such is the nature of power?  It wouldn't surprise me.  It has happened in the past, happens today (FLDS), and is the subject of dystopian fiction (The Handmaid's Tale) due to its believability. 


But this is The Walking Dead Universe, and adding a macabre walker twist to it also would not surprise me.