Separate stock, separate billing, one owner view
Each branch holds its own stock, raises its own bills and has its own day-end cash position, because those are genuinely different things and merging them helps nobody. What is combined is the view you get as owner: total sales, total outstanding, stock across both locations, and the ability to compare one branch against the other. Nobody adds two spreadsheets together, and there is no month where the numbers exist only in someone's head.
Staff see their own branch and nothing else
A counter assistant at the second shop gets a login limited to that branch, with only the permissions you tick — usually billing and receipts. They do not see the other branch's figures, your purchase rates or your margins. A manager can be given their whole branch including stock and outstanding, while still not seeing the other. That separation is what makes staff logins safe to hand out, and it is why most shops stop sharing one owner password within a week of moving.
Stock transfers between branches
Material moves between locations constantly, and a transfer recorded as a transfer keeps both stock figures honest and leaves a trail. Adjusting one branch down and the other up by hand is how discrepancies start. Where the movement crosses the e-way bill threshold — which for a truckload of cement it will — the transfer carries the values and vehicle details the portal asks for, because a stock transfer needs an e-way bill just as a sale does.
Customers who buy from both branches
A contractor who picks up from whichever shop is closer to his site should have one ledger, not two. Parties are shared across the account, so the outstanding is a single figure regardless of which branch supplied the material, while each bill still records where it was raised. That is the arrangement that prevents the common problem of a customer being over-extended because neither branch could see what the other had given him on credit.