Direction to Matrix

I’m having a hard time converting directions to rotations.
How can I orient a transform to be aligned by my directions?

transform.up = myUp;
transform.right = myRight;
transform.forward = myForward;

I risk overriding one of the assignments by the following, since direction only determines 2 axis, the 3. is arbitrary.

Best way is via a quaternion:

transform.rotation = Quaternion.LookRotation(myforward,myUp);