Hello everybody! Im new in this forum and looking for some advice as I have seen there seem to be a lot of people around here with a lot of experience and knowledge. I have started a project sewing leather seat covers for a classic Daimler Dart SP 250. I have not a lot of experience sewing leather and facing a problem at the moment. Advice and suggestions would be very much appreciated. I have made the back of a single front seat which consist of a center lined with scrimfoam and a bit in shape of a horseshoe ( I took the pattern from the original seat cover which had been made of vinyl ) which goes around the center. I have sewed it together with some piping made from the same leather and now all the leather at the top bulks up and has a lot of wrinkles. I would be very grateful for some advice about what mistake I made and how I can solve the problem. I shall add some pictures as well. Thank you for reading this!