For what i know you can't choise exactly what strategy a driver would do, but you can choise the % of cars that go on a strategy (1-2-3 stops), the lap when they come in and the interval for pitting.
For example you can choise that the 100% of the cars pit at lap 5 with an interval of 3, taht means that all cars pit between lap 5 and 8 if i'm not wrong.
You can set this opening tsm and going to the track magic data section
Hope i help you