I just read your other post on this subject.
There is nothing but the few random songs that were included on the shuffle that we did not purchase or download.
Not sure what that's about, since there are no songs that come included with purchase of a shuffle. Perhaps your kids downloaded some free "songs of the week" from iTunes Store.
Having store credit on the kids' Apple ID (via gift card) may not work with Family Sharing. If their purchase is paid using your Apple ID, will their own store credit every be used? Is the system smart enough to use their store credit first, before asking you for permission to buy and charge your Apple ID? I don't know. Please post back to let other users here know how it works in practice.
If the songs in question were actually purchased, it should appear on the Purchased screen in iTunes. You can see their Purchased screen while being signed in as you. Click your name at the top of the iTunes window, and select Family Purchases. On the your Purchased screen, next to where it says "Purchased," your first name is shown. Click your name there, and select the family member with this question. Set this Purchased screen to show Music, All, and Songs. Are those purchased songs shown there? If they are shown there, but that family member never downloaded them, he or she can log in to their Windows user account, run iTunes (and sign in), go to their Purchased screen, and download the songs into their iTunes library.
If they are not shown there on Purchased screen (and you did not see a deduction or charge anywhere), the purchase was not made. I don't know why the purchase did not happen, but you may want to try it again.
NOTE: When an iTunes Store charge is to a credit card, there may be a short delay (even one or two days) between the purchase and the charge. This is probably because iTunes Store wants to consolidate purchases (as much as possible), instead of charging your credit card for multiple "99¢" (or $1.29) charges.