I have solved this by drilling new holes in the plate that match the ones in the car, but you may find this unattractive as there will be some empty holes. I think some states may not like you "defacing" their plates, but so far Connecticut has been pretty calm about it.
The other solution I have used is cutting a sheet of aluminum the size of the plate, drilling holes to mount it to the car and adding some undersize holes that match the holes in the plate. Then I mounted the aluminum blank to the car, and screwed the real plate to it using sheet metal screws. I made sure I had enough offset that the sheet metal screws did not touch the body of the car.
Good Luck, Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)