I am planning to send the full amount of cash from a sep ira (A) to a solo 401k (C). 
The bulk of the money will go from bank A to bank C. But I (B) would like to use some funds for 60 days, and I am a bit confused. 

Let's supposed I will direct current bank A to transfer $10,000 to my personal bank B. The balance will go straight to bank C  (new solo 401k). 

From what I read on the internet, It looks that the bank will send me $8,000. 
In order to avoid any penalty or taxation, I need to return the $8,000 + $2,000 to avoid the mess. 
So my question: will the originating bank A give me back the $2,000 or it's money that will be kept as tax and sent to the Taxman? If they give back to Ira bank (A), it's like a contribution to retirement (2k withheld +new 2K)

And a complication. How Bank A will certify that I actually added the 2,000 to bank C?

Thank you so much!

 
The assumption is that we follow the rules to avoid early distribution (which is basically the 60 days).