Still confused with auto select
You only need sort the relationship by Pushups::Age in order to handle the fact that your age handles a range of ages.
As a test, add PTEvent to the layout shown in bottom right of your screen shot. If it displays the correct value, then your relationship and matching field data are correctly set up. You can then leave it like that or you can take the Score field and setup an auto-enter field option to copy the value from your table. If you set it up to copy the values, future changes to the scores in the pushups changes won't change the score for existing records--you'll have to decide whether or not that is desirable or not.
Retrieving data ...