how to compile multiple c files into one obj file using bcc32?

I have a project with 3 c files. I would like to use it in Delphi without using lib or dll, so I compile it to a obj file first and then to link it in Delphi via {$LINK test.obj}. I got success for one test.c file, now how should I handle a project with multiple c files?
thanks,
ysimon