Client/Server UDP question

Hi,
I am writing a server program which both sends and receives UDP messages to various clients.
What I want to do is both send and receive on the same port. I'd like the receiving to be done on the same thread (and therefore on the same socket). However I'd like the sending to be done in multiple threads (1 per client).
The problem is, I don't think I can use the same socket object to send to all of the clients. I'm thinking there would be collisions/problems with the multiple threads sending on the same socket.
However, if I create multiple sockets for sending, and one socket for receiving (all bound to the same port), is there a way to tell the "sending" sockets to only send (i.e., not receive)? Or is this automatically done simply because I never do a socket.receive on those sockets? Or do I need to pick a different port for sending rather than receiving?
What I want to avoid is listening to the port on my "listen" socket, but having that data show up on one of my "send" sockets (and therefore never seen, because I don't do a socket.receive()).
I've looked in the forums/tutorials for this, but nothing I've seen addresses needing to send from multiple threads, or needing to have listening on a separate thread (which I need to do to prevent having the receive() block the send()). Please bear with me if this is a stupid question; I'm new to network programming, especially UDP.
Any help would be greatly appreciated!

it shouldn't be a problem to send from multiple threads and receive on another thru the same UDP socket. If you want to send from a different socket, that's fine too... except that the other side will need to know to send responses back to your receiving socket (port) and not the "source" of the packets they receive.
I'm not sure you can mark the socket for send or receive only, but it really doesn't matter. Just don't read from the sending one or write to the receiving one. An incoming packet isn't going to block an outgoing packet, or an outgoing packet isn't going to push an incoming packet out of the way. The pipe analogy for socket connections isn't so literal like a real pipe where water could only really go one way.
It's the threads that would block on while waiting for input, which is why you need separate threads, but not necessarily separate sockets.

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