Can a married woman with children undress in front of her daughter to try on clothes assuming she would be in undergarments?
I think a rabbi would tell you pretty much what a psychologist would tell you here -- if it's a young child it's not a big deal; if it's an older child that can be a bit weird for them.
If I recall correctly, halacha discusses the permissibility of a father co-sleeping with his young daughter; if she's young enough that she wouldn't be embarrassed naked in front of him (preschool age?) it's okay.
Yes the Talmud talks about the praises about one especially modest woman who would make sure even the walls of her house wouldn't see her in any state of undress whatsoever -- but that's not the letter of the law. (And ask your rabbi whether pushing for an extreme like this is right in your situation. Often it isn't.)