Re: "Unable to play purchased songs on new iPhones (family sharing)"
If you have a Family music subscription (not just an individual subscription) everyone in Family Sharing automatically has their own Library to which they can add whatever music they wish to listen to.
Wondering if Apple support's online articles (links below) may be helpful:
(NB: Each linked article has a great deal more info, than the quoted "snippet".)
You may want to check you have "purchase sharing" turned on:
How to share apps and purchases with Family Sharing - Apple Support
"With Family Sharing, the family organizer can turn on purchase sharing so everyone in the Family Sharing group can share apps, music, books, and more."
Add a family member to your shared subscriptions - Apple Support
Eg: says:
"When you share subscriptions, each person sees their own preferences, recommendations, and shared content. When you share an iCloud+ plan, family members can't see each others’ photos, files, or documents"
You may want to check that your children's iPhones both have purchase sharing turned on.
If you can't find your family's shared apps and content - Apple Support
If members of your Family Sharing group can’t find shared content, check your purchase sharing settings,
find out whether the content is shareable, and more.
Check your Family Sharing settings
"Make sure that you're using the same Apple Account for Family Sharing and Media & Purchases. And make sure that purchase sharing is turned on. Then ask your family members to check their settings too. In order to
share purchases with your family group, you and the people you're trying to share with need to turn on purchase sharing."
________
If needed: See: How to download apps and content that your family members purchased - Apple Support
Eg: says
"If you use purchase sharing,
you can download apps and play content that your family members have bought.
If you need to check what you can share:
See: What types of content can I share with my family? - Apple Support
Apple's Music Support website: (Info. / support / contact options etc.)
Music - Official Apple Support
