The solution is to create Credit Memo in QB and then adjust the Vinosmith invoices when an account uses a credit on an invoice. For example, an invoice is paid only $220 instead of $240, with a $20 credit. When you see the invoice's "partial payment" in VS (it would leave it open for $20), you mark it paid in full.
QuickBooks Desktop Integrations: There is a setting to Track Credit Memos from QuickBooks as payments. When this setting is enabled, QBD Credit Memos applied to Invoices as Payments (in QBD) will be reflected in Vinosmith as payments. Please reach out to help@vinosmith.com to enable this setting.
Please note: Credit Memo objects are not fully materialized; no customer balances are adjusted, etc. This option purely applies to credit memo payments as Vinosmith invoice payments.