Create a shared space
Start a space you can share with a partner or family member. It takes about a minute.
Open the More menu from the tray, tap CoCarlo, then tap Create a shared space.
Give the space a name, whatever you and the others will call it. It is not locked to you as the creator: any member can rename it later from the space's screen, and the new name shows for everyone.
Then pick your own name and color for the space. These are what label every entry you make, so the others can tell who logged what without having to ask. Both are per-space and you can change them whenever you like, so you might be "Alex" in the household space and something else in another.
That is it. The space is ready to log to immediately, and you can invite people whenever you want rather than right now.
Your personal Carlo stays completely separate throughout. Nothing you log personally will ever appear in the shared space, and nothing shared will appear in your personal budget.