Hi Ian,
Substantial evidence means that the applicant must submit more compelling documents to satisfy the evaluating officer in granting the visa.
Of course, I have submitted everything that you both forwarded and I even included additional statements to address those factors that they need to consider. On the refusal letter, it says that the officer is not satisfied because of her:
Travel History
Employment Situation
Personal Asset and Financial Status
With these in mind, should we submit a new application, we must overcome these 3 factors by showing proof of travel abroad, documents showing immovable assets of the applicant in Thailand and more documents showing of her employment situation (pictures at work, original certificate of employment, acknowledgement of leave). Thus, providing again the substantial evidence when re-applying does not guarantee any visa result.