I note that it is within Congress' full purview to make Dreamers "legal" citizens, or not.

I frankly don't believe Congress should do that,, as a matter of principled belief in the rule of law.

But, if 'Congress WERE to make Dreamers "legal" citizens, or WERE to provide some sort of practical legal residency status to Dreamers, that would be Congress' decision.

It really doens't make sense, generally, in principle, to "reward" and adult's illegal act of crossing the border without authorization, or staying beyond authorization. 

Nor does it make sense from a policy perspective to make it immigration-lucrative for those adults to bring minor children across the border illegally.  It simply encourages illegal conduct to enhance a child's future -
 frankly, something I would strongly consider doing if there were a pathway for it.    

But, it IS something Congress needs to address.  And, regarding illegals/undocumented/victims of criminal parents long or short residing . . .