A common solution to the "griefing" problem in Chinese checkers is to alter the win condition. A simple alteration is: you win if your target triangle is full, and at least one of the pieces is yours. This way, a player can't block you from winning by putting a marble in your target triangle (or leaving one there if they started there). It's not foolproof, though, as three players farthest from you can form an impenetrable blockade pretty quickly if they want to grief. Perhaps a more generalized solution to griefing is this win condition: you win if your target triangle is full of your marbles, or if you have no way of filling the triangle further, in any number of moves, if your opponents don't move.
