Total Team Members with correct Team Leader

Hi, I'm new and hello!
I need direction on what type of formula to use.
Looking for a way to total team members to team leaders. Array of Sumifs!

Example..

Member1=1
Member2=5
Member3=12

Member2 is on a different team, so the answer I need is the total of 1&3 which would be 13.

Please see spreadsheet.

Many thanks