I have an upstrem server and three remote locations with 3 downstream servers how do I know which client is being updated at the different locations,Thank you

I have four WSUS servers in total . 1.) Upstream server using port : 8530 the other three servers which are Downstram servers are at different remote locations but I can actually see them and connect to them .Qustion is how can i verify which server is updating the clients at remote locations .Thankyou