Yes, I do speak of Seidokan. I woder what is practiced in this Udundi system that you speak of. Is the curicculum available? I know that Matsumura, after learning the Palace Hand art went to China and learned the Shaolin arts. Upon his return he joined them together to make Uchinade, or Okinawa Hand. The Palace Hand art is a Minamoto art handed down by the Motobu lineage, or thus it was taught this way by my Sensei. Sensei also said that Uehara Seikichi Sensei only learned a small portion of the Motobu family art. He was acquainted with Choyu Motobu and this information was said to have come from the source. I know Motobu Choyu Sensei did do some forms like Huquan and Baihe. These forms I do not believe are now taught. I am sure we each change our art to fit us and learn what we can from those who agree to allow us to gain knowledge from them.
If you are curious, my Sensei was Hanashiro Shinyei, who studied under Chosho (not Choshin) Chibana who in turn studied under Sokon Matsumura. He passed away earlier this year at the age of 99.
The People formerly known as Paul Hart