There should be several sites in here to give you some ideas.
Did the Declaration mean only white men? only white men with property? all people, including freedmen and freedwomen? all people except slaves?
wait but what does the word reconcile mean in the question
How could the people in the 1700s (especially those who were writing the Declaration and later the Articles and the Constitution) agree on the idea that all men are created equal at the same time that many of them and lots of others owned slaves? Did they think slaves were not men?