Power Query - Append and merge tables

Another day, another power query headache that I can't get my head around.

I am working with multiple tables each containing partial data that I want to merge using Power Query. Each row shouldn't contain any conflicting information, however most rows contain null values which I'm looking to cross reference and replace with the correct values where they exist.

Note that for some instances there will not be any valid data which then need to remain as null/blank in the final output.

Any help with this would be really appreciated.

I've just used that on my actual dataset (approx 160k rows over a dozen tables) and it has worked perfectly!

Thank you so much for your help as always!!