Cody has offered you excellent advice.
I would also recommend putting a small playground area on top of the cage. Put a couple of favorite toys and maybe a treat on the playground.
Don't try to force Coco and Lulu out of their safe environment, it should be their decision to come out if/when they are comfortable doing so.
Cody's suggestion of allowing them to step up in the cage and then seeing if they are comfortable being placed on top of the cage is spot on!