Unfortunately I can not see any other way than the explanation as below. I am using a local server.
I have five tables.
Table 1 is called 'Genres'. Columns here are: 'id', 'id-name1', 'id-name2', 'id-name3' and id-items'.
Table 2 is called 'Category 1'. Columns here are: 'id' and 'name1'.
Table 3 is called 'Category 2'. Columns here are: 'id' and 'name2'.
Table 4 is called 'Category 3'. Columns here are: 'id' and 'name3'.
The last table named 'Items'. Columns here are: 'id', 'itemName'.
All 3 Category tables containing multiple-choice buttons. Its content is saved in 'Genres' table as described above.
Just as your guides describe is Item-insert page created with server extension 'Multiple Record Insert'. Any Category table has its own 'Multiple Record Insert'.
Update site is created using 'Manage Relational Table'. Any Category table has its own 'Manage Relational Table'.
I get an error message when I open the insert page in the browser and fill out the form and press send.
So I wonder if it is supposed to use your server-ons 'Multiple Record Insert' and 'Manage Relational Table' to create a form with several multiple-choice buttons in the same form.