I have a Raspberry Pi 3 running windows 10 IOT core with a backgroundapplication1(BGA1) running on it.
Can i start another backgroundapplication2(BGA2) from BGA1 ? and terminate BGA2 from BGA1 ?
No, you cannot. Background Applications:
launch at machine startup and run continuously without any process lifetime management resource use limitations
So all background applications are started when the machine starts. And they control their own lifetime (by choosing to exit), but nobody else can directly shut it down.