I'm in the same process right now for a 4 year old who lost her mom. The mother's clothes ( since she was only in her 20's ) are mostly cotton knits. I am treating them just like I do T-shirt quilts and using a very light weight iron on interfacing. Once that is on, you can cut them up and use them any way you wish. Or you can keep the whole and use them that way. When it comes to putting them together I often use cotton sashing and cornerstones. I use a cotton backing with Warn and Natural batting. I quilt them just as any other quilt on my home machine. Hope this helps you and good luck with this project. I'm sure the quilt will be well loved by the little girl.