Separate people from asset types
Start by deciding whose investments you are tracking, then group the information by asset type. This avoids creating a separate spreadsheet system for every family member.
Use a shared set of definitions
Decide what counts as invested amount, current value, gain, liability and net worth, and keep those definitions consistent. Otherwise changes over time can reflect a change in calculation rather than a change in the underlying finances.
Review the household picture
Once the information is organised, review the combined picture as well as individual portfolios. This can make it easier to see concentration, cash reserves, debt and the family's overall wealth position.
Keep privacy and access in mind
Financial information is sensitive. Use a system with appropriate access controls and share only what each person needs to see.
Put it into practice with FolioTrack
Once you know what you want to measure, the next step is keeping the information organised so you can review it again later.