Hello @bright,
in general, when you add extra fields in a content type, don't use a database field name which is already existing in Joomla #__content table.
Now, if you really want to store your 3 wysiwyg fields in the same database column, you must use the custom storage like that:
- field 1 => custom | Article | column_name[field1]
- field 2 => custom | Article | column_name[field2]
- field 3 => custom | Article | column_name[field3]
The column don't necessary need to be "introtext". you can add those 3 fields in a new column.
Best regards.
Lionel