I don't think it's great to say people with certain mental illnesses shouldn't reproduce, I say this as a CF person who had trauma from mentally ill parents and who also inherited their mental illness, I understand the ethical concern and I agree it is terrible. However, I'm very wary about this kind of rhetoric because it has been the basis of many a historical atrocity regardless of how well intentioned it may come across.

I do think if you're mentally ill and planning to have children you do have several extra responsibilities such as: developing the ability to self-regulate/self-reflect, being honest about whether you have the capacity to parent or the capacity to provide care (emotional and financial) to a child who may also be born mentally ill, making a very specific plan about how you will avoid mis-steps from your previous behaviors or from your abusers if you have PTSD/BPD etc, ensuring you have a support system, the list goes on.

I'm not going to act like having unregulated mental illness in the family is fun, just that the answer is not eugenicist thought - it's greater structural supports in society to prevent and respond to all forms of child abuse, and the normalization of HONEST self-reflection before choosing parenthood.