I have written about the importance of keeping your beneficiary designations current on your IRAs, life insurance policies and so forth. It is also important to coordinate the distribution of those assets with the distribution of the assets in your trust.
When designating beneficiaries, you don’t necessarily have to use the form that the company provides. I do recommend starting there, but you should feel free to attach your instructions to the form rather than trying to fit everything into their form. For that matter, you are not obligated to use their form and can create your own form.