Syncio operates on three main rules with how inventory is synced up.
These are the conditions that trigger an automated inventory/ product adjustment:
For the source store:
A manual inventory adjustment (can be from an inventory transfer).
An order is received.
For the destination store:
A paid order is created (Syncio can be updated to support pending payments on request, available for Shopify only).
If a sync is active and healthy then inventory quantities across all connected stores for synced products will match.
Other conditions that trigger a sync:
Updating a product attribute on the master source product (for example: updating the description, adding a new tag, deleting an image, etc).
Stock syncs both ways when a refund on a paid order is made.
Pending orders need to be marked as paid and then refunded before a reverse stock sync can be made.
Shopify Order Edits: see guide