This is from the AP, reporting from sources, and it’s all very new:
At the moment, this is more confusing than anything, because the policy change came from the top down, and now it at least appears that those at Homeland Security are trying to change it from the bottom up. It may be that the pressure got to Kirstjen Nielsen—she has been the face of Trump's child separation policy for the last few days, and the public reaction has been swift and severe. She even had her dinner interrupted Tuesday night by DSA activists.
On the question of whether Trump will sign, there's this second ambiguous tweet from the AP:
It could very well be that he’s going to sign Nielsen’s order to end family separation. We’ll update as the story develops.