If you copy video from Panasonic HDC-TM700 / HS700 / SD700 directly (without using Panasonic HDWriter), the HDWriter won't be able to join them. But there is a workaround:

1. Download and install multiAVCHD
2. Launch multiAVCHD
3. Drag'n'drop your MTS files onto onto multiAVCHD
4. Choose "Destination path"
5. Hit the Start button
6. Under AVCHD for solid media
   Hit the 1080p@50fps if you use a PAL camcorder
   or
   Hit the 1080p@60fps if you use an NTSC camcorder.
   
   Also select "Panasonic HDC-TM/HS/SD 700" in the "Force specific camcorder Maker/Model list.
   
   
   
7. Format your flash card using your camcorder.
8. Insert your flash card into card reader (or connect your camcorder using a miniUSB cable)
9. Go to the PRIVATE folder on your flash card and replace the AVCHD folder with the one created with multiAVCHD.