I want to build a full-scale Law Firm MIS in Google Sheets. The objective is to create a centralized management system covering the entire firm — Legal Operations, HR, Finance, Admin, Business Development, and PR/Branding — with a top-level executive dashboard. Broadly, I need: Legal Operations Client-wise task analytics Overdue tracking (based on internal due dates) Associate workload Reviewing authority oversight Deadline intelligence (today / this week / next 30 days) HR Headcount dashboard Leave tracking Hiring pipeline Basic performance indicators (task completion, overdue ratio) Finance Client-wise revenue tracking Retainer vs non-retainer split Monthly revenue trend Expense tracking Profitability view Outstanding receivables + aging summary Admin Compliance calendar Vendor tracking Asset register Recurring expense tracking Business Development & PR Lead tracker + conversion rate Proposal status Revenue from new clients Content / engagement tracking Master Executive Dashboard Active tasks + overdue risk Monthly revenue, expenses, profit Receivables position Headcount Active leads Compliance alerts The system should: Be modular (separate sheets per function, but interconnected) Auto-update Be clean and structured Be scalable for at least 2–3 years of data Primarily use formulas and pivot tables (Apps Script only if necessary) This should function as the firm’s central management control system. Let me know how you would structure this, estimated timeline, and whether you’d recommend phased implementation.