Didn't read either apparently.
Look, we've had this discussion before. You claim Lincoln's actions were unconstitutional; and then I point out that he was acting under the authority granted the government by the Confiscation Acts, the constitutionality of which were upheld by the Supreme Court in The Prize Cases (67 US 635) in 1862; to which you will reply something about a biased Supreme Court, blah, blah, blah; and nothing will be accomplished. I'm just short-circuiting your plans by not playing.
There is a constitutional clause REQUIRING slaves to be returned to the people to whom their labor is due according to the laws of the state that holds them.
No lesser act of congress can override that. It simply does not matter what congress says on the subject, because the Constitution itself says they have to be returned.
If you want a fig leaf, Lincoln could have ordered his army to force the states to abolish their laws, but what he can't do is free them when state laws hold them, and the constitution requires those state laws to be enforced.