Not illegal. A little research goes a long way mate. Try it.
Most of those separated from parents crossed at official border points seeking asylum, which is fully legal. Even those who didn't, it's classed as a misdemeanor, on par with public drunkenness. So there's no criminal activity here (unless you are foolish or naive enough to believe anything Trump, Miller, Sessions or Huckabee Sanders says).
These people have commited NO crime, and yet they now face indefinite detention, and those families already separated have no idea where their children are, no clue as to how they find them, and are getting no assistance whatsoever from the US government. Trump's latest photo-op signature is as meaningless as Chamberlain's white paper. It does NOT solve the problem that Trump himself created, and it does NOTHING to prevent the ongoing illegal detention and abuse of thousands of children who still have no future with their parents. 78 kids have even been passed to an adoption agency. Yes - an ADOPTION agency.
This isn't about right or left, it's about right or wrong. Continuing to keep these families apart and incarcerated is WRONG. and Trump hs done nothing to solve the problem he caused.