Need help with sewing a flower dress - lining fabric?

Use a basic poly lining from your local fabric store or if you think your daughter will be more comfortable, use a poly/cotton broadcloth as a lining. You should have no trouble finding tulle for the net ruffle in a coordinating color. Another possibility is a pre-make trim if your store has a larger selection. Unless the bride is super picky, you want the pattern to be an inspiration and to use your own creativity for the details.