Are you saying that you want to position one sprite relative to another?
This would be used when a ship fires its weapons.
I program in C++, but the languages are similar when it comes to the Dark GDK commands.
I would use:
dbSprite(2,dbSpriteX(1)+dbSpriteWidth(1)/2-dbSpriteWidth(2)/2,dbSpriteY(1)+dbSpriteHeight(2),dbSpriteImage(1));
to position a shot in C++.
This should be close to basic.
I guess it would be like this:
Sprite(2,SpriteX(1)+SpriteWidth(1)/2-SpriteWidth(2)/2,SpriteY(1)+SpriteHeight(2),SpriteImage(1));