Additional Assignment info: Effective start date field (custom EFF) is not visible in VBS

Summary:

We have created a custom EFF for Additional Assignment and effective start date field is auto populated with employee start date and this field is not available in VBS.

Our requirement here is to have a validation rule for start date (Start date >= Effective start date)

for this we need to have a validation rule to display error message if start date is entered wrongly.

Currently there is no effective start date field visible in VBS for any of the EFF page

Please let us know how we can achieve this.

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