Could you please help me with understanding the aggregated value of multiple account for FBAR filling.

I have 3 account.

This year had $5100 in account A, then transferred $5000 to account B which had already $100, and later transferred this money to account C. 

So after several days, I had the following balance A - $100, B - $100, C - $5000. 

As I understand I did not had aggregated value more than $5100.

Is that correct?

What does the rule says about the day of the transfer. It seems that on the day of the transfer I had $5100 on account A and then $5100 on account B, although in reality I had only $5100 in value.