is it possible?
Separate the offending item(s); saveas R12 or R13 then reload or block into your drawing. (Or skip the first part if you don't mind losing some of the newer (14,2000,2000i,2002,2004) information.
Grab SPL2PL.VLX from http://www.dotsoft.com/freestuff.htm. It will convert them in place with no DXF/WMF hoops to go through. Terry