Given that moving slaves around was outlawed before slavery in the Empire I am not sure what you mean.
Ah, this is an interesting point. Was the moving of slaves around illegal, or was it just the international trading of them? i.e. if there was no monetary exchange involved, would it be illegal under the terms of the 1807 act?
If it is that the slaves are freed in 1840 (after the six years of indentured apprentiship) then they are free to move wherever they want to.
I was thinking it might be possible for some status that is not slave but not fully free. So they were technically free men, but they did not have the rights of white men, and the government could decide to force them to migrate.
However the problem will be money. By this time the sugar production has peaked and they had too many people on the Caribean islands as it was.
Given the racism of the southern states, they may have been willing to pay for the export of their black populations just to be rid of them. It would be a lot cheaper to export them to the Caribbean than Africa. Given the sugar industry was on the way out, the Government might just decide to write off these islands economically, and use them as a dumping ground for unwanted blacks. Sure, the overpopulated living conditions for black people would be horrible, but that's not the sort of thing that would worry Westminster too much.