Renzo DemartiniIn short
- Decide which system owns each record before you choose a connector, a rebuild or a new platform.
- Connect in this order: a native link, an integration platform, then a custom API or MCP link; replace only when a system itself is the problem.
- Fix cash and compliance records first, and keep a retired system’s records for as long as the law requires.
Your billing system says a customer owes A$18,400. The ledger says A$17,900. Which figure goes in the board pack?
Every system you add brings a possible link to each of the others. The answer is rarely a new tool; it is which system is allowed to be right. That is a CEO decision, and it comes before any connector or rebuild.
Automating payroll, AP and the month-end removed more than 500 labour hours a year
My own work
500+
Labour hours a year removed
By automating payroll, AP and the month-end, from 2023. Hours, not dollars: no cash saving is claimed.
Since
2012
When I started building business systems
An MYOB cloud migration and cloud payroll.
Source: About Renzo
Decide: replace, connect or leave
Connect when the systems work; replace only when one of them is the problem
| Choice | Fits when | Cost | Decide |
|---|---|---|---|
| Connect | The systems work, but the data does not move between them | Upkeep of each link | Before you renew a licence |
| Replace | A system is unsupported, cannot export, or blocks how you work | Migration time and a period of risk | When the board sets the date |
| Leave alone | One person uses it and nothing depends on it | A gap later, if it grows | At the annual review |
Replacing is the dramatic answer and often the wrong one. A system that does its job but sits alone is a connection problem. Replace one only when the system itself fails: it is unsupported, it cannot export its data, or the way your team works has moved past it.
Ask each system one question. If it vanished tomorrow, what would break, and who would notice first?
Name one owner for each record
Every record has one owner, and the other systems read from it
| Record | Owner | Read from it by |
|---|---|---|
| Customer details | CRM | Billing, support, reporting |
| Customer balance | Ledger | Billing, CRM, reporting |
| Supplier bank details | Ledger | Payments |
| Staff and pay | Payroll | Ledger, reporting |
| Jobs and quotes | Job system | Billing, ledger |
One owner per record: 8 systems need 11 one-way feeds, not 28 links
8 systems
28 → 11
Possible links against one-way feeds, for the 8 systems in the list
5 records
5 owners
One system and one named person for each of the 5 records
A model built from the owner list, not a count of a real business. Pairs of systems: n × (n − 1) ÷ 2, so 28 for 8. Feeds: each owner sends to each system that reads its record.
Illustrative figures, not client data.
The owner is the system whose figure wins when two disagree. Pick it by who maintains the record, not by which tool is newest. Write the list on one page and give each record a named person.
A difference is a symptom, not an answer. Set a limit, say A$100, above which a gap goes to a person who finds the cause. Then connect one way: the owner sends, the others read.
More detail
Where the Privacy Act covers the business, the Australian Privacy Principles expect reasonable steps to keep personal information accurate, up-to-date and complete (OAIC, APP 10 guidelines). One owner per record makes that easy to show. Get privacy advice where your situation is unclear.
Three ways to connect
Try the native link first, then a platform, then a custom API or MCP link
| Way | Fits when | Who looks after it | Check first |
|---|---|---|---|
| Native link | Both systems already offer one for the record you need | The vendors, and your finance lead | The limits: a marketplace app may make 110 requests every 10 seconds per account (HubSpot) |
| Integration platform | Several systems, or a rule such as a gap limit, sit between them | A named person in the business, or an adviser | Which products it supports: n8n lists hundreds of nodes |
| Custom API or MCP link | No ready link exists, or an AI assistant must read the record | A developer or adviser, with a written handover | Who holds the keys. A private HubSpot app is limited per app and per day |
Try them in this order. A native link is one the two vendors already offer. An integration platform such as n8n, Zapier or Make sits between systems and can hold a rule, like the A$100 limit. A custom API or MCP link covers what has no ready connector.
I work with any system that has an API key or an MCP connector. Whichever way you choose, ask for three costs: the licence, the build and the yearly upkeep of each link.
More detail
Where this comes from, checked on 25 October 2026. n8n’s documentation says it supplies hundreds of nodes to create workflows that link multiple products. The Model Context Protocol is an open-source standard for connecting AI applications to external systems. HubSpot’s usage guidelines limit each account that installs a public marketplace app to 110 requests every 10 seconds. For privately distributed apps, the burst limit applies per app. The daily limit is shared across all apps in the account. Vendor limits change, so check the current page before you design.
A platform can hold a rule. n8n’s Filter node filters items based on a condition. Zapier’s filters let a Zap continue only if the data meets a set condition (page updated 29 May 2026). Make’s filtering passes a bundle to the next module only if it meets the conditions.
Fix in order of what a wrong figure costs
Start where the money and the legal duty sit, and leave the rest
Fix first
- What customers owe
- What suppliers are paid, and their bank details
- What staff are paid
Fix second
- Reports the board relies on
- Quotes and jobs that feed billing
Leave for now
- Rarely used systems with no dependants
- Anything you plan to retire
Order the work by the cost of a wrong figure, not by which link is easiest. Cash and compliance records go first: what customers owe, what suppliers are paid and what staff are paid. Reports that only inform come second. A rarely used system with no dependants can wait.
Supplier bank details need the most care. Change them in one place, the owner, and let the payment runs read from it.
Switch a system off last
A system is safe to switch off only after its records are out and open
- 01Take a full export
Transactions, attachments and history, in a format you can open without the old system.
- 02Prove it opens
Open it in the new system or an archive and check a sample.
- 03Switch off after sign-off
Turn it off only when both checks pass and a named person has signed off.
Before a system is retired, take a full export and open it somewhere else to prove it works. ASIC says companies must keep financial records for at least 7 years, so the old system’s history has to be kept for that long, in the new system or an archive.
What to do first
One page of owners shows you where the rework comes from
- 01List your systems
Every system that holds a customer, supplier, staff or money record.
- 02Name an owner for each record
One system and one person, decided by who maintains the record.
- 03Connect one way, native link first
Start with the record that costs most when it is wrong.
- 04Review the exceptions weekly
Gaps that do not close go to a person, with a date.
A one-page list is enough to start. Begin with the record that costs most when it is wrong.
Common questions
Should we replace our systems or connect them?
Connect them when they do their job and only the data fails to move. Replace a system when it is unsupported, cannot export its data or blocks the way your team works.
How do you connect business systems?
Name an owner for each record first. Then use a native link if both systems offer one, an integration platform such as n8n, Zapier or Make for rules between several systems, or a custom API or MCP link for what has no connector.
What does it cost to connect business systems?
It depends on the systems and the way you connect them, so no fair figure exists without a list. Ask for the licence, the build and the yearly upkeep of each link.
What is a source of truth?
The one system whose figure wins when two systems disagree about the same record. Each record has one, and the other systems read from it.
Can we do this without new software?
Often, for the first step. Listing the systems, naming owners and reviewing the exceptions need no new tool. Connecting them needs the systems’ own links or a platform, and someone to look after each link.
Chartered Accountant (CA ANZ) and finance executive, based in Canberra. Practical AI and automation for SMEs, and adviser to owners, CEOs and boards on integration and finance.