/cgl/ - Cosplay & EGL

I apologize in advance if this is a really dumb question, I just don't want to fuck this up. I recently bought two vintage dresses that are as long as the picture. I bought them in hopes I could alter them to be lolita dresses. If I wanted to make the skirt part shorter would I hem it from the bottom, or remove it from the bodice and take it in, then reattach it? Either way, would it look too weird/frumpy with a petticoat underneath after I'm done?