Here are some suggestions from The Coalition to Support Grieving Students about how to approach the funeral or memorial service with children:
Explain in simple terms what will happen.
Where will the service take place? Who will be there? What is likely to occur? Will the casket be open? Will people be telling stories of funny or pleasant memories? Will there be a lot of crying? Invite and answer questions.
Let your children decide whether or not to attend.
Don't force them to participate in any ritual or activity they find frightening or unpleasant. Let them know it's OK to take a break for a few minutes or leave if they are uncomfortable.
Find an adult to be with each child.
Especially for younger children, find an adult who can stay with each child throughout the service. This person can answer questions, provide comfort, and give the child attention and support. It's best if this is someone the child knows and likes who isn't directly affected by the death, such as a babysitter, neighbor, or staff member from school. This adult can focus on the child's needs, including leaving the service if the child wishes.
Offer a role in the service.
Children may appreciate a simple task, such as handing out memorial cards or helping to choose the flowers or a favorite song for the service. Suggest something that will comfort and not overwhelm them.
Offer other options.
Younger children may want to play quietly in the back of the sanctuary or meeting area. This still gives them a sense of having participated. Older children and youth may want to invite a close friend to sit with them in the family section.
Check in afterward.
Be sure to speak to your children after the service and offer them your comfort and love. Over the next few days, ask what they thought of the service. Do they have any feelings they want to share or questions to ask? Are themes from the service showing up in their play or drawings?
More at https://grievingstudents.org/module-section/funeral-attendance/