Giving back games??

[MidMadness]

Need some feedback on etiquette for giving back games in H.S.??? I have a full sub-varsity schedule at this time, I have been at it 4-5 years now...I am starting to get calls (2) ..asking if i would be interested in doing Varsity?? Of course I say yes, they say they will send me a schedule next week. I didn't dare give them dates I couldn't work seeing how I have been waiting for these calls for a while now...... When I receive my schedule is it right to call my other assignor who already gave me the sub varsity schedule and give the games back?? Or should I tell the assignor with the varsity games that I can't work certain dates?? anyway, I am babbling, you get the jest of what I am getting at..Any help would be appreciated..Thanks