I've always liked the name Dylan for a girl... it's short and sweet, yet packs a stronger, more masculine punch since it's connotation is usually for a boy's name.
However, if you're all set on the middle name Jean, (a lovely choice by the way) I would go with Daisy. Daisy Jean rolls off the tongue easier than Dylan Jean, in my opinion; it's catchy and perhaps even slightly reminiscent of Michael Jackson's 80's hit "Billie Jean". The only downside of Daisy as far as I can see is that it could be considered a little too sweet and ultra feminine.
I don't mind Dylan for a girl. However, with Jean as a mn and with your combination of Cash & Stone, Daisy just seems so perfect. Like someone said, a nice wild west theme that's not too over-the-top because the names are simple and adorable. I think a little 10 yr old Daisy might be happier with her name than a Dylan, too. Daisy Jean is beyond adorable.
Dylan just feels very different to me. More modern, more British Isles...