Fetch or Keep Away?

Have 2 shitzu’s I tell them it’s bedtime one runs upstairs jumps in bed the other one scrambles for a toy gets it then drops it at the bottom of the stairs for me to throw it upstairs then she retrieves it and runs to bed. Every night we do this. Sometimes I have to chase her to get it from her. But she will not go up unless I throw it to the top. If it goes halfway she waits till I get it to the top.