jearef wroteMy suggestion is to call your JV assigner now, and ask him what his position is on these situations.
Ch1town wroteAlthough turnbacks may be frowned upon, there are always exceptions to the rule(s). It's the way you go about it that matters most.
I absolutely 100% agree with these two posts. Call the JV assignor and be COMPLETELY HONEST with him/her. Believe me, assignors talk to each other. They will find out if you try to be sneaky or give a false reason for turning back the lower level game.
Josh, from Iowa, gave you one side of the coin. In his area, it is strongly frowned on to turn back a game for a higher level game. In my area of Massachusetts, it is pretty much a given with all my assignors that I am allowed to turn back any game for a higher level game with no repercussions. This is true from middle school to college.
Either way, be honest about it. If the JV guy is hard-nosed about it, then you'll know that for next season and you can honestly tell the Varsity assignor that you've taken a game from Mr. X that you can't get out of. I hope for your sake that the JV guy is reasonable. Good luck.