You will have to disband the Family Sharing group and form a new one. You do not say what age your children are and this is critical. In theory you can all leave the family group, but if your children are minors they have to be transferred. This has to be initiated from the account of the current family sharing organizer. Since she is deceased you have to take this up with Apple. It may involve you getting control of her account. For information about how to request access to a deceased family member's Apple account data, and possibly their equipment, read this support article --> How to request access to a deceased family member’s Apple Account - Apple Support "For security, Apple requires and verifies legal documentation before we can assist with a deceased person’s account. This generally includes a death certificate, and may also require a court order or other documentation. The requirements vary by country and region. We have great sympathy for surviving family members and try to help with requests as much and as quickly as possible."
Read this support article about managing membership of a family sharing group --> Leave Family Sharing - Apple Support
Follow the shortcut to:
- How to leave a family sharing group --> Leave Family Sharing - Apple Support
- How to remove anyone 13 or over if you are the Organizer. --> Leave Family Sharing - Apple Support
- Disband a family group --> Leave Family Sharing - Apple Support
If your family includes children under 13 (age varies by country or region), you must first transfer them to a different Family Sharing group or request that Apple delete their accounts entirely.
Move a child to another group using Family Sharing - Move a child to another group using Family Sharing - Apple Support
On your iPhone, iPad, or iPod touch
1. Go to Settings.
2. Tap Family. If you don't see Family, tap your name, then tap Family Sharing.
3. Tap your name.
4. Tap Stop Using Family Sharing.
Any family member age 13 or older* can remove themselves from a family group. If you have Screen Time turned on for your account, the family organizer must remove you.