Short of an all steel or steel hardware cloth coop, you aren't fencing out the squirrels.  You gotta get control of the feed so they cannot eat the feed.  If these are "babies" that is tough to do as they will be too small for a rat proof chicken feeder and treadle feeders are not safe for birds under a pound or two.
If I were you, while the chickens are small, I would feed twice a day and no more than the birds will clean up.  That will stunt their growth a bit, fewer eggs if you have some adults, or better yet pen the babies apart and use a rat proof feeder for the adults.
But to defeat squirrels you HAVE to stick with the narrow and distant treadle, no extra platforms to make them easy to use.  You have to keep the spring pretty tight so they can't gang up on the treadle or just push the door open.  Even then, enough squirrels are gonna defeat a treadle feeder but there is a silver lining, they make great squirrel traps.  Drop the feeder in a trash can with a lid and run a hose from the lawn mower into the trash can for ten minutes.  Or take Mr. Squirrel for a very long car ride.
The good news is if this is indeed a family, a litter with near grown juveniles, once they are grown the parents will force them to leave so you won't have five to deal with.  But it begins again next litter.