David, I know you said you dont want to seperate your females, but by doing so you will be able to better to monitor your new girls on their eating, weights, and their poops. But I would also consider feeding in several ways. One put in several food dishes, one female may be dominating the food dish thus the others are not eating as much as they could. But also sometimes when stressed in a new environment they dont know what to look and with so many new smells they could get confused, so by offering 3 lids in there in 3 different locations, it will offer your girls several places to stop and eat from. My other thought is maybe they dont enjoy that particular feeding ledge, maybe they would prefer it more if it were solid. TO fix that you could go with the other ledge and drill a hole like you said and you could use some of these cups http://www.pangeareptile.com/store/2-oz-shallow-portion-cups.html http://www.pangeareptile.com/store/3-4-oz-cups.html
Or take that wire ledge you have now and place something over the bottom of it so that it is easuer for them to walk on.
Before trying the baby food, here is an idea, a much healthier idea at that. Take a mango, peel it and put it in the blender with a little bit of water and puree it. Take your CGD and instead of mixing it with water, take the water portion of it and make it half mango and half water, then mix with the CGD, it will sweeten it up without adding in the junk that is in baby food. Another way is to take mango nectar (you can buy it at the grozer store, i normally by looza brand, you can also use peach and apricot) and make ti the same way as with the mango puree, half mango nectar, half water. Again a healthier way to sweeten it up.
Another option is to try using part 2 diet and change the flavors up, I personally keep fig and mango part 2 at the house because I have 2 gargs and 1 picky male crested gecko and find they eat OK with the CGD but eat like champs with the part 2. It can be used as the main meal instead of the normal CGD, it is the exact same stuff except the favor is different. http://www.pangeareptile.com/store/two-part-gecko-diet.html
If those dont work then I would try the baby food route last. If you try using the mangos and find they really like it, maybe consider getting the mango part 2 diet to feed them.