Novi has set out to make your day-to-day easier when it comes to handling member transactions. The most important thing to note is that Novi lives on the revenue side of the P&L (profit and loss, or income statement). We deal with member records - Quickbooks calls them customers.
In short, Novi only deals with transactions that touch customers. Novi operations do not affect transactions relating to your expenses or your vendors.
That being said, one instance to make note of where your vendors may be very minimally affected is if you have someone in QuickBooks Online as a vendor who also has a record in Novi.
QuickBooks will not allow a vendor and a customer to have the same name. The solution here is to find the vendor record in QuickBooks and simply add "- Vendor" as part of the display name. That way, your data is clean in both Novi and QuickBooks.
Note: If there is a customer address, phone number, fax number, or email change in QuickBooks Online, Novi will update the address in its record as well.