Please include a version number of BLS-2014 with your support question (26.05.##). Now this is not a bug report, just that it's a good practice in case a feature was modified for a particular version number.
You might be able to do this carefully, if you completely finish your season before assigning any prizes. It further would be incumbent that every team have a playing strength of four, but have a roster of five because what I will describe would do denominations for five team members, for all teams (not possible in BLS to have some at 4 and others at 5).
Back up your league in it's current, regular rules configuration. If you do web uploads, do not upload after doing this (or revert/restore back to the backup just done in regular configuration). After you have everything finalized, go to your rules and change the playing strength from 4 to 5 bowlers. Your prize lists for team items will all be divided by 5 bowlers, but again that will apply to every team.
If you have some teams bowling with 5 and some with 4, view your prize denomination breakdown in 4-bowler configuration, and make note of those teams with 4 and use those numbers...then change it to 5 as above and make note of the numbers for the applicable teams there. You can always change it back to 4 when done.
You will have to be careful and have your final standings all set because a change in playing strength from 4 to 5 can affect points results, handicaps, etc.
Always check, download, and install the most recent update of your software to ensure that issues may have been corrected.