Hello there.
The title itself is quite explanatory. We are aware that the group reward functions through a command. My suggestion is to incorporate a straightforward panel for member searches. This panel could include fields for entering names and account names, as well as a space to specify the reward prize.
Considering that the F6 panel is already quite comprehensive and adding a button might be challenging, my proposal is to access this new functionality through a command, such as /greward.