The Custis estate was supported in grand style by the labor of slaves.
That was Lee's official residence while in the Army. That is like my official "home of record" while I was in the Navy for 20 years. I was never stationed at home and did not see a whole lot of it.
There is absolutely no question that there were slaves at Arlington. That does not make Lee their owner.
The Custis family was certainly supported by the labor of slaves. I have not seen evidence that Robert E. Lee was being supported by the Custis family.