it would be impossible to do without making DC an actual part of maryland, and then maryland would have undo influence -- indeed, outright ownership -- over the seat of government. not to mention the administration of the facilities, buildings, monuments, & etc. . . .
I think it would be possible to have the grounds of federal property (the Capitol, the White House, whatnot) NOT part of Maryland. I'm thinking of the private businesses and residential neighborhoods being part of Maryland.
I've been worried about this a very long time now, as you know the Democrats are sooner or later going to pull off a coup getting one House seat and two Senate seats, if this isn't quashed permanently. And the Democrats have been looking at places such as Puerto Rico, the Virgin Islands, Guam, whatnot, to get even more guaranteed Democrat seats in Congress.
This is of great concern to me.
This is why, when Republicans gain control of Congress again, this should be a "high priority" matter, either quashing it permanently or making it easier for red states to break themselves up into multiple states, so as to erase that advantage.
In a perfect world, the District of Columbia wouldn't even have a "delegate" in Congress--no one after all is FORCED to live there--but this isn't a perfect world.