> You can add new fields only (probably, you can also change
> name of existing fields but not datatype, length etc.).
> If you want to change something, then you can 'Generate Script'
> then edit it (basically it's CREATE TABLE... command),
> drop existing table and generate new one.

You meant there is no tool like "MODIFY STRUCTURE" that
could automate the 3-step process in SQL Server's utilities?

What would happen if I adjust the system catalogues for the
tables? Will it allow me to do so?