A colleague here at Means I/O tells this story:"This weekend, my wife said to me, 'Google says I'm almost out of storage! and I was like 'We have 2TB with Google One, that's not possible!' "What was the problem? Well, just because you set up Family Sharing with your Google Account, you don't automatically start sharing your extra storage from Google One. You need to turn it on.
First, the basics:Google One is essentially the paid version of Google Drive. It gives you extra storage space (beyond the free 15GB) to use on Drive, Gmail, and Photos, and lets you share that storage space with up to five family members. Plans start at 100 GB for $1.99 per month or $19.99 per year. If that's not enough, you can go up to 2TB for $9.99 per month / $99.99 per year, or if you really have has plenty to store, plans go up to 30TB for $149.99 per month.
(If you're still on a free Google account and don't want to switch yet, you can go to the Google One Page to take advantage of a tool that can help you free up extra storage space, though you'll have to resist the urge to shop in Google One.)
If you want to share your storage, you must first create a shared family group. Here's how:
Once you've set up your family account, you can then set up your shared storage:
Your family members can now share storage space with you. This means that once they have used their free 15GB, they will have access to the extra storage space your account gives them – it does. not mean that you have access to their files, unless they share them directly with you.
If you want to see how much storage each member of your family is using, go to your Google One account, click "Storage" on the left side and select the down arrow next to "Storage family”.