Yes, what you’re referring to is known as incremental refresh, and since last Fall it is available for Pro users (previously only Premium users). Check out the post below from EDNA Expert @Harsh , which includes extensive resources on setting up and using incremental refresh.
As to the first part of your message, I’m not sure when you say “combine the two data sets on our CRM”, whether you are trying to do that restructuring within the CRM itself or loading the data into PBI and doing the transformations within Power Query? The latter definitely should be possible, although I’m wondering how many records we are talking about?
– Brian