Section 3100(a) states the general rule: in making an order under the joint custody chapter the court shall grant reasonable visitation rights to a parent where it is shown that visitation would be in the child's best interest as defined in § 3011 and consistent with § 3020, and in its discretion may grant reasonable visitation to any other person having an interest in the child's welfare. The second half is why non-parents — a step-parent, a long-term carer — appear in these orders at all.
The rest of the section is about safety. Subdivision (b)(1) provides that where a protective order under § 6218 of this code or Penal Code § 136.2 restrains a parent, the court shall consider whether the child's best interest requires visitation by that parent to be suspended, denied, or limited to situations where a third person specified by the court is present, including virtual visitation. A parent may propose a name for that role, and the court may order supervised visitation with that person — but submitting a name neither requires the court to order supervision nor amounts to agreeing to it. Paragraph (2) requires the court, in deciding the type of visitation with a restrained party, to consider the nature of the acts that led to the protective order, how long ago it was made, and whether there have been further acts of abuse. Subdivision (c) applies a parallel analysis where an ex parte custody order under § 3064 was warranted because a party's conduct presents a risk of immediate harm to the child or of removal from California.
Subdivision (d) governs the drafting of the order itself where domestic violence is alleged and a protective order has issued: the visitation order must specify the time, day, place and manner of visitation, including virtual visitation, and of any transfer of the child, so as to limit exposure to conflict or abuse, ensure the safety of all family members, and minimise the opportunity for abuse including coercive control. Those details are the substance of a safe order, and they are worth working through with a family lawyer or a domestic violence advocate.