I'm sure there's been suggestions about ideas before but this one is one that is used in a baseball gm sim I recently joined.

They have a group option in the pending contract sections where you can group players into 1 of up to 10 groups if you choose to do so.

This is a copy of their instructions...
Use the groups drop-down to optionally group free agent offers together. As soon as one player from a group signs, all other offers in the group will be set as inactive. To re-activate an inactive or rejected offer, click 'Edit' and submit it again. The free agents with the most 'Activity' will evaluate their offers first.

For example, group could allow us to make offers to multiple QBs and if one of them agrees to terms, then you don't sign any more. It could also be used to group higher salary players so you dont blast past the cap.

Just a suggestion, hope it helps or gets the ball rolling.