One wallet. Every adult in the family.
┌──────────────┐ ┌──────────────┐
│ son · SF │ │ ma · Indore │
│ budget: 1.2k│──│ spend: 870 │
└──────────────┘ └──────────────┘
▼ shared ledger ▼ma's pharmacy line, the brother's mess fee, the standing chai-budget — all one ledger. Roll-ups by category, by person, by month. The family treasurer (it's always one of you) stops chasing receipts on WhatsApp. Sub-cards live inside this wallet as one of the controls.