Milling and whipstock assembly with flow diversion component

A method of performing aspects of a milling operation, the method comprising:

• deploying a milling assembly in a borehole, the milling assembly including a mill having an internal fluid conduit in fluid communication with a borehole string, the mill including a fluid port configured to connect the internal fluid conduit to an exterior of the mill, the fluid port located within an interior of the mill, the internal fluid conduit connected to a second fluid conduit that extends from the mill and the internal fluid conduit to an anchor, the milling assembly including a moveable flow diversion component disposed in the mill and configured to move axially in the internal conduit within the mill from a first axial position in which fluid is prevented from flowing between the internal fluid conduit and the fluid port, to a second axial position in which the internal fluid conduit is in fluid communication with the fluid port and fluid is permitted to flow through the fluid port and the mill;
• controlling fluid pressure in the internal fluid conduit on the flow diversion component to move the flow diversion component from the first axial position to the second axial position, wherein movement of the flow diversion component is guided by one or more pins extending into the internal fluid conduit and engaging one or more slots formed in the flow diversion component, the one or more slots defining a path that directs the movement of the flow diversion component;
• and
• circulating fluid through the borehole string and the mill and rotating the mill to form an initial section of a secondary borehole that extends from the borehole.