Sorry nevermind. I found it in the options.
I've a similar problem problem with SDDM 3.3
I have a table with PK and UK T1.
I've created a new table T2 when i create a Foreign Key from T2 (with parent T1);
even if I choose to use the UK the utility put the column of the PK in T2.
I can make an correct association with the UK only I've just created the columns on T2
Is a bug?
Is a bud configuration?
Thanks for reporting this problem. I've logged a bug report on it.