Custom Option/question On A Particular Gallery

Hi! 

Can anyone think of a way to ask a question or include options just on a specific gallery? 

I've got multiple jobs using the same price list, but only a few of them are taking place over 2 days, and I would like to have customers let me know when they register which day they want their photos done. Some are Tues/Wed and some are Thurs/Fri.

But I don't want to ask this on ALL of the galleries using that price list. Just wondering if anyone can think of anything other than creating separate price lists for each.

I know you said you dont want to create a separate pricelist, but did you know you can duplicate pricelists with one click?  So your regular Pricelist is now EXACTLY THE SAME but you've called it PRICELIST-CHOOSEDAY and you add in the extra field.  Very handy.

Yeah, okay I might just do that ;) :-)