SSRS isn't a data entry tool, so I don't think you're going to get what you want from there. However, if this is pulling form CRM, you can do it there. Make sure you have two fields, your dropdown list, and a text entry box. Then set a rule in your SSRS
report to use the dropdown as your default value for a column, and if that value is blank, use the free text column.
It should be as easy as:
if isnull(field1)
then
(field2)
That will pull all the data you need from CRM and your users can enter it there, where it can be retained for later reporting as well.
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