I do not believe that there is any way to send only one type of message to one server and a different type of message to another server. I do not believe that an access list will do that either - but you are welcome to test it and let us know the outcome.
You can use ip forward-protocol/no ip forward-protocol to control what kind of messages get forwarded by ip helper-address. But whatever set of messages are enabled are sent to each server.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...