Sorry I didn't see this info until now!! I'm going to reply here instead of on the PM we have going incase someone else could benefit from the conversation.
For my rescues while they are sick I use 10 gallon tanks for each gecko. It is very important that they are housed seperately at this point so they have minimal stress and you are able to properly monitor each gecko. Sometimes geckos can become extremely thin and stressed just from being housed with others, so my first suggestion would be to get them into their own homes asap!
If you're keeping food items available at all times, after you've separated the geckos, try removing all the food items for the day. Don't pick up the geckos during the day or disturb them much if possible! In the evening, leaving them in their tanks, try taking an un-dusted mealworm with tweezers and slowly putting it on the ground in front of the geckos (work on one gecko at a time, so take about 10 mins trying to feed each gecko). Make sure the mealworm is moving around, poke at it gently with the tweezers or pinch the mealworm's butt to get it to walk or move. Be patient.. if it goes out of the gecko's reach, put it back in front of the gecko & repeat as many times as the gecko will keep eating them or even shows an interest. Try on both sides in front of the gecko incase it has better eye sight on one side, you never know! This is what has worked for all my rescues so far, but only works if they are being housed alone. I also suggest putting a bottle cap half full of Plain calcium with NO D3(very important that it's only calcium) into each gecko's enclosure only for the first week so they can re-stock, & fill water bowls every day with fresh water. Try and let me know how it goes! Fingers crossed for you!!