To make the Juno dress with an extended button placket you will need to create a longer button placket piece. Use dot and cross paper, greaseproof paper or regular paper to make your pattern.
Use the existing pattern pieces to work out how long your button placket will be. Use pattern pieces: Dress back (B) and Back Neckband (E)
Draw in the stitching lines/ seam allowance on the neck edges on both the Dress Back and Back Neckband. Line up both pattern pieces along the stitching line.
Draw a line from the extended centre back all the way down to the hem (its approx 1cm all the way down). Draw in the stitching line/ seam allowance at the hem.
Cut off the extended Centre Back piece or fold over so you can re-use the pattern for a different placket.
Make a new button placket piece by measuring from the top of the neckband to the drawn in seam allowance at the hem and using the width of the existing back placket (13.7cm wide). You can write your pattern piece details on this piece – size, cut 2, pattern name etc. Draw in a fold line along the length of the placket half the width of the placket.
Re draw the grain line on the Dress Back -this is now not cut on the fold- instead cut 2.
To make up the extended version button placket:
Interface both button placket pieces.
Overlock down one long edge of each placket, making sure you overlock the opposite side to make a pair (a right and left placket)
Overlock the bottom hem of the dress.
Fold one placket in half lengthwise, right sides together and sew across both of the short ends and trim the seam allowance to half. Do the same with the other placket making sure you have a pair of plackets.
Place the raw edge of the placket piece together with the back of the dress (right sides together) and match the seams at the top of the back neck. Refer to pt. 17 in the original instructions. Pin and sew along the long edge. On reaching the bottom hem, sew over the seam of the placket as you did the top.
Trim the seam allowance down by half. Press the raw seam allowance towards the placket and press along the fold line. The placket is now ‘bagged out’ and the hem is rolling to the wrong side of the dress. Do the same with the other placket piece before pressing up the hem evenly.
Top stitch the button placket down and hem the bottom of the dress- starting from the top of the back neck, round the hem and back up to the other side of the back neck.
Sew horizontal buttonholes every 10cm or so to one of the plackets and buttons to the other.