I had a few week olds that really weren't eating much because they thought the crumples were too big and I suspected they were hungry. So I tried the mash thing. Now I have a mix of week olds, 2 week olds & 3 week olds and I give them a pan of mash for their breakfast every morning. I use warm water. They see that pie plate coming and they practically stampede me!
I also have been using this time to introduce the newer younger ones. I give them a day in their own brooder to make sure they are eating and drinking and behaving normal. Then on the second morning as soon as I put down the mash pan I add the new chicks. They quickly join in on the feeding frenzy. Much happy peeping is heard. When they are all full and sleepy they go take a nap together and the older ones never realized I added the newbies.