I am new to this forum but would offer the following hints. I have made custom drapes for several years for an interior designer.
1. Sew all panels of lining together and all panels of fabric together. Press seams flat. We do not clip our seams? Should not be any puckering if tension is correct on machine.
2. Press up 8 inches along the bottom of fabric then pres in half so that you have a 4 inch double hem. Blind hem. You will want to put a 2 inch double hem in the lining. Don't forget weights in the hem.
3. Measure from your finished bottom hem to get finished length and press at top. Add buckram under double hem.
3. Press 1 1/2 inch double hem in each side (after trimming off edges).
4. Lay fabric flat (right side down) and place lining on top of fabric (right side up). Line up seams if possible and pin in place. The bottom of the lining should be about 2 inches shorter than the fabric. Tuck the lining underneath the top header and pin in place. Tuck the lining under the side seams and press so that you have a trim line if lining is too big. Trim off excess lining on the sides and hand sew in place along the full length of drape. Don't forget to miter your corners.
5. Mark pleats and stitch.
Q