NTT

Noro sensei said that in Japan 2nd form, katate dori or gyaku katate dori, was the basis, in a martial logic. When he came to Europe, he found out that people in France shook hands, right hand to right hand. He then decided that 1st form or Aihanmi Katate Dori, would become the basis.
1st and 2nd form shape the basis of all other forms in 2 respective families of techniques.
1st form would evolve into 3rd, 5th and 7th forms.
2nd would evolve into 6th and 8th forms.
4th form would be done either by 1st or 2nd form. He did not appreciate 4th form as being grabbed to the chest lit his temper to a higher degree...
I do not know if Noro sensei did those links in his first days in Europe.
I will inquire on the beginnings of the forms and manners. It is a question which did not come to my mind!