I am looking for information on how to pass a custom variable (transaction_logID) to the square API and then have it returned back to me on the webhooks notification URL response.
How can i specifically link a "charge" event with a "notification" event so that I can update my personal SQL record with the transaction result? (Approved, Declined etc)
Thanks for your help.
Unfortunately passing in custom data and getting it back in a webhook isn't possible.
Depending on what exactly you want to link your notification to, you can look up the ID from the webhook in the v1 payments endpoints.