Is it possible to link the random girl folder with the random girl files. So if someone wanted to build a certain girl, they would not need to find images to go with that girl.
I'm not sure what you mean.
If you want a girl to only use the default images, don't make a folder for her and the game will automatically use the defaults.
If you want a random girl to use the images for a non-random girl, make a .rgirlsx file with the non-random girl's name.
If you want a non-random girl to use images from a random girl, make the .girlsx file with the random girl's name.