I realize the purpose of define-type is to create structs, but I have struct with some constarints that must be satisfied, like in define-type.scm

I want two vars, 'x' and 'twice-x', where twice-x = (* 2 x)

In my code, I have created good-x-set! and good-twice-x-set!

However, how do I overwrite the existing linked-x-set! and linked-twice-x-set! with my good-x-set! and good-twice-x-set! ?

Thanks!