I am making small pies (in muffin tins!) for a party. I plan on pre-cooking the filling (ground beef and veggies), then finishing the pies at the location. Would it be helpful (either for transport or for shortening the on-location cooking time) to par-bake the pie crusts in the tins?
The reason to par-bake your pie shell is because it would not cook through in the same time that the filling does.
So it depends on what type of filling you are going to use. For example, if you are using a traditional short crust with a cream (custard) filling, the custard will probably cook faster than the crust would, so you would want to par-bake the shell.
On the other hand, for an apple pie with a deep layer of fruit, by the time the fruit is cooked through, the crust usually is too, so par baking is not required.
In your specific example, you have not said what the filling is, that you are precooking. However, if it is essentially fully cooked, you could blind-bake your shells then just put them together to heat through for service. You would need to share more details to get more specific advise.