convert rgb to cmyk

Good Morning:


I have downloaded a Free vector (.cdr) file which was designed using RGB color.  This files has 100's of objects that are in color with RGB..

Is there a way to convert the RGB color's to cmyk without having to do each one by hand?

Maybe some kind of "Macro?

I need to do this because I am going to have this design printed on a T-Shirt and the printer uses "CMYK 4-Color Process" for their printing.