Selecting the replenishment course can be more of a challenge, depending on sea state. Replenishments are routinely conducted in sea state 4, with highly skilled personnel on both ships they can successfully be conducted in sea state 5. If the guide is yawing 1.5 degrees, it is a judgment call based on skill and experience, as well as operational necessity. And if the guide is yawing as much as 2 degrees on either side of base course, it's probably not possible to safely conduct a replenishment. Replenishments will normally be conducted on a Romeo Corpen that best satisfies both ships' follow on commitments, but in extreme conditions the sea state will determine the course, and even whether the replenishment is possible.
Quartering seas are the worst possible situation from a shiphandling standpoint.
Once a Romeo Corpen is agreed upon and the guide ship is steady on that course and speed, the receiving ship's next task is to come to waiting station. The duty of the guide ship is to steer the agreed upon course and maintain a constant engine speed. Both ships will have gear tested and stations manned to at least the same standard used for sea details at arrival and departure from port. The purpose of waiting station is threefold. Second, it provides the approach ship an opportunity to accurately gauge the guide ship's course and speed.