Thanks  

I am currently using Option 2, and I am thinking to move to Option 1 since we do need add to new sources as time goes. It will be fine to move the deduplication from the current "Single step (after union)" to a later step, e.g., when the downstream consumers read the "multiple source delta table". 

Another solution, I was wondering and was testing, would be to convert to Declarative Streaming table with multiple flows. My observation is the "DLT with multiple flows to single streaming table" behaves the same as the Option 1 that we have been discussing. 

Do you have more input and suggestions. 

I will mark the thread with "Accept as Solution".