I am using black lines, but you can download same courts with white lines too.
You don't have to change your all courts, you can change only some of them (just take a look at files names)
instructions:
1) download rar file (one of two)
http://qler85.wrzuta.pl/sr/f/2yzN2TYWm6 ... lack_lines
http://qler85.wrzuta.pl/sr/f/5gplVTnV1z ... hite_lines
2) unpack rar file
3) copy unpacked files to directory (default) C:\Program Files\Dream Match Tennis Pro\Data\Models (you have to replace oryginal files so I suggest to make copy of all replaced files first)
HARD

HARD2

HARD3

CARPET

CARPET2

CLAY

GRASS
