Mom won't stay on eggs-help needed

[Aspen Meadow chiq]

We had one chick hatch two nights ago. He soon figured out how to get out of the nest, mom followed to take care of him and left her eggs. Another hen then babysat the eggs for her When I discovered all of this I put mom and baby back in the nest and they were ok for about 12 hours. I've had to put mom and baby back on the nest about 4 times since (48 hours) and still no more chicks. The eggs haven't been abandoned for long, I have had to lock them in then let her out every few hours for food and water.
She's a great mom to the chick but she still likes her eggs too. She's most happy when sitting on both.
So my question is, how long can eggs be cold before they won't hatch? and how long should I keep doing this?

 

[steve232]

If mom is taking baby out to forage shes done with those eggs. Usually all the eggs that are going to hatch do so within a day or so of each other. Sounds like the others just aren't gonna hatch for what ever the reason. Mom knows best. Theres no better way to raise baby chicks than having mom do it.

 

[chickens really]

I always Brood Momma on eggs in my Broody pen. I place feed and water directly in front of her so the hatched pop in and out to eat and she continues to set the other eggs.