When primary role is "fill" let us put a role we DON'T want as secondary
I love being support but I don't always want to be support when I select fill. I sometimes want to be "anything except support." Or "anything except adc" because I suck. Right now primary fill leaves no second option, which is logical since you select every already, but I think it would be GREAT to still leave a second option for a role you don't want to fill as. Right now, queuing as fill guarantees being support 95% of the time either set as primary or secondary. It makes no difference from selecting support as primary or secondary and this would give a really distinctive value to the role "fill."
Please for your consideration.
EDIT: and idea proposed in the comments would be that AT LEAST you can choose the role you played last as a role you don't want to play. That way you fill and maybe play one game as support but not the next.