I think that is an excellent idea. 23 and me, Ancestry, Family Tree DNA, and any other of those DNA/Genealogy websites. They need to prove that their ancestry is African and they were in the United States as a slave between 1787 and 1862. Because if they weren't living in 1787, when the Constitution was ratified, then they are the UK's problem. 1862 was when the Emancipation Proclamation was signed, so if they weren't in the United States prior to that then they could not have been slaves.
Plus they should all be given 40 acres and a mule, as promised, instead of money. The Federal government has seized a ton of land in the western states. 79.6% of Nevada and 63.1% of Utah is owned by the Federal Government. So there is a whole lot of BLM land (Bureau of Land Management, not Black Lives Matter) that they can give to those who prove they were descendants of slave. Western Arizona has a whole lot of wild mules that can be rounded up and domesticated for use on the 40 acres of land.