If i undestand right, you need something like:
IF → in_AccNumber Is Nothing or in_LegalTool Is Nothing or in_Reason Is Nothing or in_Comments Is Nothing → then “next” → else “run the next activity”
Let me know if this statement is ok or needs further help.
You can write a if condition in your process xaml as you written above…and on then side if you throw error it will write exception if you leave like that it goes to sucess…both works…as you need
On the els esid eyou can have whole of your process
Ir you are using reframework, just below the get transaction item, in the same if that you assign the item to the transaction item, add those validations in that if, so if any of your variables is empty then don’t assign any transaction item and move to the next transaction, if it has value then just assign it and continue the transaction