Dual Disc Encoding (PAL/NTSC)

Hello, I'm interested in making DVDs to send to my family. I have spent some time learning Kdenlive and love it; it's a great free editor and does everything that I need. My only issue is that I have some family members in NTSC-land and others in PAL-land. I want to maintain the highest possible video quality for the DVDs that I create (I'm an engineer working for a media company). I have a Canon HF-10 1080p camcorder, and my workflow for my first DVD (which I've encoded for NTSC format) is like this:

1. Move the Mpeg-2 transport streams off of the camera onto my workstation
2. Run a script which calls my own AVC decoder and FFMPEG to scale and transcode the video for editing
- the output is a mezzanine format: about 18MBPS all I-frame MPeg-2 in an AVI container
3. Edit with Kdenlive, cutting clips, adding transitions, adding captions
4. Output titles in MPEG-2 format, 6mbps, 720x480 progressive
5. Gather multiple titles together, create menus, and author the disc with DVDStyler

So I have all of this working for NTSC and now I want to produce an identically edited DVD but in PAL format, with the highest possible video quality and the minimum possible effort. :) I'm hoping I can do something like this:

1. Modify my script from step 2 above to do frame rate conversion with FFMPEG and scale to 720x576 instead of 720x480
2. Write a script to hack the .kdenlive project file so that it will use the newly encoded input files in PAL format
3. Run the kdenlive project to do the editing and encoding to DVD-Pal format
4. Make a new DVDstyler project or tweak the old one to author a PAL disc

So I would like to request some help from any kdenlive developers or gurus with regards to step 2. In particular I'd like to know which XML fields in the project file I would need to modify in order to successfully 'drop in' a different set of input files with a different resolution and/or frame rate and still handle all of the transitions and captions correctly. What would really be great is if I could also in the future drop in the original 1080p streams and be able to encode an HD output stream.