The best option for your bridesmaids might be a skirt and top. Here is a selection of sewing patterns for modest midi skirts (that is, tea-length, mid-calf, etc), that are specifically designed for special occasion fabrics such as satin, taffeta, georgette, chiffon, crepe, and crepe de chine.
Simplicity Sewing Pattern S9109 Misses’ Wrap Skirts In Various Lengths With Tie Options. Suggested fabrics include crepe de chine and silky types.
Simplicity Pattern 1369 Misses’ Skirts in Three Lengths. See views A and B. Suggested fabrics include brocade, crepe de chine, satin, and taffeta. View B overlay fabrics include chiffon, georgette, and organza.
Simplicity Pattern 2058 Misses’ & Plus Size Amazing Fit Skirt. Suggested fabrics include crepe, crepe de chine, and double georgette.
New Look Pattern 6271 Misses’ Skirt in Three Lengths and Pants or Shorts. Suggested fabrics include crepe de chine, double georgette, and silky types.
Vogue V9090 Misses’ Pleated Skirt in Three Lengths. Suitable fabrics include satin.
Butterick B6772 Misses’ Skirts. Princess seam skirt with front slits or ruffles at seams (the ruffled version is modest). Suitable fabrics include crepe and double georgette.
McCall’s M7355 Misses’ Crop Top and Gathered Skirts. Suggested fabrics are satin, taffeta, and shantung, plus sheers for overlays.