Finishing a lace edge?

Hi there! My daughter is slated to be a flower girl in my sister's wedding, and while looking for dress ideas I came across this one: https://www.etsy.com/listing/212635377/lace-flower-girl-dress-junior-bridesmaid?ref=market I'm toying with the idea of making something similar using the Fairy Tale dress pattern. I have not worked with lace overlays before--does anyone have tips on how to finish a lace armscye on a sleeveless dress? Comfort is as important as asthetics, because my 5 yo balks at anything itchy and I need to avoid a flower girl diva meltdown. :-)